Click here for a Multimeter ➜ amzn.to/2SNGZkw Click here for new spark plugs ➜ amzn.to/2Mb6JFa Check out these other informative videos: Fix Stripped Spark Plug Threads For Free With This Hack ➜ ua-cam.com/video/yY_fuDRltZE/v-deo.html How To Diagnose and Read the Color of Your Spark Plug ➜ ua-cam.com/video/Tz4uxFMUCOA/v-deo.html Check For Spark On A Mower, Chain Saw or Other Engines ➜ ua-cam.com/video/VZ8r7xv3DLY/v-deo.html Make sure to check out the Saloon here too… Click here for my website ➜ www.stevessmallenginesaloon.com/ Click here for my Parts and Tools Store ➜ www.amazon.com/shop/stevessmallenginesaloon Follow me on Facebook ➜ facebook.com/stevessmallenginesaloon Follow me on Instagram ➜ instagram.com/stevessmallenginesaloon/ Follow me on Twitter ➜ twitter.com/SteveSaloon The resistor is there to suppress radio frequency noise which helps protect car radios, mobile phones and engine management systems. AND some ignition modules require a resistor plug to allow the coil timings to work properly.....
Old mechanic once told me to test a questionable spark plug you must first fill a 5 gallon bucket of water, then you must toss the spark plug in the 5 gallon bucket of water, finally observe the spark plug. He then said, "if it sinks then it's bad. Replace it." ;)
??? What??? Resistor for suppressing some noisy waveforms? You must be kidding! Chuck in a couple of ferrites will probably be of a better option if that is really your concern.
I just watched a guy test for spark at the spark plug of a mower that wouldn't run and had good spark, and from that moment on he tore into that mower to try getting it started but failed. As a last resort, he installed another spark plug and the mower cranked over and ran good. I did a similar thing testing for power at a washer machine with a neon test lamp, it illuminated and I starting tearing into that washer when I had a though, go out and buy a multi meter. I got home and the multi-meter and the 120V receptacle only showed 90 volts. I followed the wiring back to a junction box, removed the cover, and found a poor splice connection. I re tightened the splice connection, soldiered it, and got the 120V for the washer. You can't beat experience. I enjoy your channel, thanks for sharing.
Thanks for this Steve. Keep them coming. I'm now single after 30 years and never did anything like this, plus I lived in a major City. After moving to a rural location and needing chainsaws, log splitters, etc, your clear, concise videos are a big help in keeping them running and diagnosing when they aren't. It's a 3 hour round trip to get a spark plug and You have to order them first. Repairs are also stupidly expensive even for simple things and it's nice to know whether you are being told truthfully What's wrong, not just have parts replaced to bump the cost. I've found a woman on her own can run into that sometimes.
MrsGraphiteGal Another quick tip on a chainsaw or other motor, if it is not starting a quick check after trying the choke, and the regular starting instructions. Take out the spark plug to see if it is "bone dry", means there is NO fuel getting into the combustion chamber.Likewise if the electrode part is wet with gas, then you know it is gas fouled-won't run. At least you can know right away what is going on in there right quick if you are far from the shop or far from town etc. Good luck and Smart gal reading and watching this stuff. Also good practice to set your chain brake before trying to start- a sharp chain can cut you when it is not rotating, but not as badly as when it is moving fast.
Thanks Keith. I'm adding to my knowledge every day. Luckily my grandad was a master carpenter and my dad an engineer in the Royal Navy, I think I've inherited some of their creative abilities. Don't worry, I am VERY careful with the chainsaw, never use it without at least trousers and gloves even when diagnosing it for a few minutes. Although, the guy who services it says not to use the brake when starting as newer chainsaws don't need it and it actually causes problems with the huskies. I still use it, if rather replace a part than my limbs !!
In High School Auto Shop we had a spark plug tester. You screw the plug into a small air chamber with a window on it. You add current and you can see the plug begins to arc.....but as you add air pressure (compression) a bad plug begins to stutter and fail under compression. That was a learning moment for me.
@@NMranchhand I'm 61 now.... I've messed with engines since I was about 13...when your dirt bike keeps fouling plugs (or other things)..... it's either fix it or push it....so you learn to work on things. But yes...this fact still makes me wonder how compression effects spark. ua-cam.com/video/pl24m9utZLo/v-deo.html
@@readmore3634a cleaned plug will fire a dirty plug will fail the spark takes the path of lest res. (dirty plug) carbon build u on the porclin post bottom of plug its easyer to flow thru the carbon on that post to ground that jump across a gap so it fails --clean the plug no fail
Thanks Steve! Great information. My Pressure washer would not start. After watching this video I checked, and replaced, the spark plug. Starts easily now. Total cost $3.71!
Steve, thanks for the spark plug video. I asked several people about a spark plug tester. They said there was not one. Saw your video, and brought a multimeter. Sure beats putting in a new spark plug when the old one is still good. Thanks for saving me money!!!
I'm in my fifties now, and I've owned multi-tester meters ever since I was a teenager --- you are absolutely right; even just a simple "no frills" unit is a total life-saver in sooooo many circumstances, such as when you're checking for the presence/level of voltage/current, testing for wire-breaks/shorts, etc.
I recommend better than “no frills” because my USA made fluke was able to find continuity issues in 3 resisters on a Deere mower OSHA safety board (ignition, seat switch, blade-PTO). Sent it to TV repairman who said the resisters were fine using his own Chinese(Communist PRC) multimeter. He was wrong, My fluke was right. Diesel motor had vibrated the wire ends of the resisters to form cracks.
@@hugoglenn9741 Yes, the cheapie ones do tend to break down after a fairly-short time. Even the costlier-model Micronta testers from Radio Shack didn't last --- they suffered worn-away rotary-switch contacts, just like the bargain-bin-grade meters often do.
Hey Steve, I had a beer with you watching your video!!! I learned something today! Only after 50yrs. being a car and ambulance mechanic! I'm learning more and more how to keep the small engines running on my lawn tractor, weed wacker, chain saw, etc. HOW DOES THE OLD SAYING GO, YOUR NEVER TOO OLD TO LEARN SOMETHING NEW!!!! THANKS STEVE!!!
When I was a VW mechanic back in the sixty, we has a spark plug tester. You cleaned the plug first, check gap, place in tester, some worked fine until you put 120 psi and no spark, a lot of plugs work fine until you put them under compression pressures and then no workie! My two cents worth.
Ive had that. Mower wouldn't start. Tested for spark with the spark plug on the engine casing. Sparked ok. Put back in and engine wouldn't start? Eventually tried another spark plug and the engine ran. It took me about an hour to figure it out plus a lot of swearing!
Yes! My father was an old time mechanic, and he had a spark plug tester. When I was a kid learning about cars, he demonstrated how a spark plug could spark fine at low pressure, but fail at high pressure. I couldn't believe it when I saw it. I couldn't believe why pressure would make any difference, but it did. It's something I never forgot.
Greetings from TEXAS. The resistor plug in the automotive industry is to help on Radio Frequency Interference for computers and of course the good time radio.
EVERYONE KNOWS THAT THE ''R '' IS FOR RADIO FREQUUENCE INTERFERENCE... if you do not know that then you are uneducated and need to go back to school...
I had an issue with my mower yesterday, I watched several videos but I couldnt solve it. Watching Steve solved lot of my issues also got to learn how to fix my mower. Thank You Sir!
I had a lawn mower given to me last summer and that was the only thing wrong with it. It was a Honda with an NGK. Those plugs are prone to foul out if the carburetor was been flooding. I used to buy a case of them every winter for my snowmobiles. I always carried extras in my pockets for my buddys. They NEVER had spares on long runs. On older snowmobiles, it was normal to have carb issues. Good video. I wish more guys would just go out and buy a spare plug for all their small engines. Especially chain saws.
....very worthwhile video. I'd waited till it was dark to test for sparks on the plugs for several old machines or even old new cheap machines I never touched in years. I had a few suspicions, you've pointed out defiinet things to check through. The clincher is some spark plugs have a resistance and 5k is actually a lot . I couldn't understand why all of a sudden one machine no longer showed a healthy spark . I'd been interchanging plugs on the machines . Fancy that , the Dickens you say , never knew plugs could have resistance .
As always, an awesome video and GREAT ADVICE Steve! Whether the others know it or not, all your videos are actually teaching people HOW to troubleshoot and that there is a proper progression to follow... (ie: not just jumping into throwing out the existing plug without checking IF its causing the problem) I was taught that from my (electrician) father over 50 yrs ago, I continue to (try?) and teach that to my sons to this day, but they’re all part of the ‘instant gratification’ society and, like on their video games, want to hit a reset button. To them, the time to just put in a new part... is ‘quicker’. Ask my 30 yr old son that now after buying a new battery for his truck, replacing the starter, THEN calling dad when it still wouldn’t start... Added 20 litres of gas, turn the key, VaRooom! Problem solved!
I agree about the kids and their video games.....I try to teach my 14 year old how to stuff and he gets impatient so fast... they're used to push button instant results.
Haha... I'm trying to teach my 16 year old kid the same thing. Dear Lord give me patience.... why do these kids think that when I'm lookin n thinkin n not speaking.... it's NOT a cue to head back into the house and I'm to "text you when I figure it out"! Jeez! Pulling stunts like that will summon Momzilla....and that crazy lady won't tolerate a lazy smart ass. Even if I have no bloody damn clue what I'm doing! I'm out here on a wing and a prayer with UA-cam videos and a stubborn ass personality. I hate to pay someone to do something I can learn to do myself. I'm a hard head but I'm finally fixing more things than I'm breaking further....so that's nice.
Yes Steve great advice. Was north of Inuvik and my chainsaw failed. No spare plug. Found out it was the coil shorting and used some grease from an axle bearing to run down the crack. Got the road opened and back to civilization!
I keep a neon sign transformer handy at my shop. 7,500 volts and low amps. With wires to a spark plug it simulates the ignition system voltage and a fouled out plug will sputter and smoke till the fuel burns off. Good for testing and if the ceramic isn't soaked with fuel the transformer will quickly clean up the plug to be able to use it.
Fantastic, as always. Thank you. Just a small note from an electronics guy: if the dielectric material (ceramic in this case) has a crack, the item which can leak between electrodes is current, not voltage. Love your channel.
Not entirely true. If there is a crack and it is not contaminated, the meter won't find it, but the high voltage coming through the spark plug wire will break down the air in the crack and act like a short. Kind of like a static discharge.
@@EngineerHank, then, there’s the compressed fuel/air mixture within the cylinder to which the energy has to overcome to cause ionization of that mixture. But, you already know this.
I tested a brand new kit of Magneti Marelli, 3 reading 5.4K and 1 reading 3.6K. I saw also the original technical manual of NGK and they infomed 3K to 7.5K as normal on resistive spark plugs.
Eliminating any potential cause is good. Knowing why a particular part failed is far better. I dig your videos, man. Thank you for taking the time to share knowledge.
Just did battle with an old 8 hp Briggs L head for two weeks, new points and coil ( which were corroded and not producing spark), rebuilt carb etc... couldnt get it to run properly , was driving me crazy then watched this video and discovered bad spark plug. I should have known better, this video was a good reminder for me. Have one on me......
I'm still using your videos when I'm lecturing. You're great! I'm teaching tomorrow and using you and Billy Ray. You really help my boys. You teach really well, at their level. They're between 17-60. You're between saving them and bringing on the next generation. If you're ever in the UK we would love to see you. Thank you so much. p.s, I'll buy the beverage!
Mate you made my day! I was testing the riding lawn mowers plugs because its engine was not having the right attitude. It was running, but once you clutch in the mower it did not have the torque it used to have. So I checked the plugs and, R-type, it was showing 4,7K on the one, 12,9 on the other plug. Voila! Problem solved. Thanks to your easy instructions on how to properly test spark plugs.Things can be so easy if you know what you're doing!
Good detail for the beginners. Thanks for this. A Lot of folks don't give ignition the respect it deserves. As a Master in the 70's spent a lot of hours keeping customers Eight-cylinder engines running strong on all eight. The good thing about a one -banger is, you always know when a cylinder is weak - because its the only one! -Sandy
Your videos are great Steve. Thanks for sharing you experience and knowledge. I wanted to share something that I think is relevant to this video. Just because a plug passes the test you outlined in this video does not mean the spark plug is in "good working order". I just replaced a BPR6ES in a mower with a GCV160. The mower would start relatively easy but after about 30 seconds it would die out. I was thinking carburetor\fuel issue but quickly ruled that out. Compression was 90+ psi with decompresor so wasn't too worried about that. The mower had good spark and the plug passed your test, 4850 ohms, and no continuity on the threads\body. The plug had pretty heavy carbon deposits that I cleaned away prior to the test. I replaced the plug anyways and my issue was cured 100%. So the question becomes...were the carbon deposits to blame? If I cleaned the existing plug and reinstalled it would it likely work just fine?
The correct gap is important . I just had a Briggs & Stratton 7 H.P. that would not run . The gap was .025 . I set it to the correct gap of .030 . It started on the first pull . Thanks for the information .
Helpful info, but for all non-resistive type of plugs, you will find that your multimeter will not be able to detect a crack in the porcelain insulator inside the body of the spark plug. The spark will jump across that point and also possibly the spark plug as well gap due to the high voltage of the ignition system (depends on where the crack is) but the spark may be very "weak" at the spark plug gap. Your multimeter on the other hand works on very small voltage for continuity and testing resistance so it will not be able to detect the crack in the insulator and as such the multimeter will read open or infinite resistance even though your spark plug insulator may be cracked. There is a case where carbon may build up inside the gap and short out the center conductor to the outside case. In this instance you will see a high resistance reading but it will not be infinite on your multimeter. For resistor type of plugs, these scenarios are also true, however you need to consider the 4.7 K ohm resistor in your measurements. Hope this helps.
Good checks and ideas. I saw a guy being neighborly and helping his neighbors with their mower doing prelim tests. He couldn't see the arc of the plug clearly from pulling with it facing away and could see spark. He continued and found lots of marginal issues. He fixed each one or improved it spending time and materials on each aspect of good ability to run, basically refurbishing their whole machine. When he was through, he was a-pullin and a- cursin. His spark would rather arc to the outer circle (to ground) than jump the gap from center electrode to side electrode. He did closer spark testing and got a good look. Then he did what you said. Grabbed a plug from another and fired it right up Cost him a Saturday and a Sunday instead of a plug. Plus a plug , after. No charge. Nice guys finish last sometimes, but all his refurbishing, debatably, Did his neighbors machine some good. And the you tube audience was entertained if you saw what some of us saw right off.
Steve, you are right. I am not in this line of business and I don't have a good spare plug sitting around. I need your method to get a yeah or nah of my current plug. Thanks much.
When I do my pre-season "Get-er-ready" routine, I pull the plug, wire brush it, lightly file it, and re-gap it. I have a 27 year old Honda 8hp Snowblower with the original plug. Do you thing I've gotten my moneys worth out of it yet. I have other 20+ year old engines that I've done the same. Good spark plug toss and thanks for sharing your vast knowledge.
Hey Steve, if I may call you Steve, otherwise sorry, I had gotten one and only one that tested good by both tests, it turned out to be and well-insulated spark plug threads the fix was to PB blaster and then tap out the threads with anew spark plug tap. this clean out the threads to make a connection with the cylinder head I asked the owner what he had done had taped the spark plug outside and wet brushed the cylinder head with a radio vanish that he had found on his grandfathers' workshop and had seen how sharp his grandfather lawnmower looked. he was thinking that the old man just cleaned and then varnished those lawn equipment. but the spark plug was loose and the varnish just sucked its way into and between the inside threads and the outside threads of the spark plug luck would have the varnish was for 20K Volts transmitter plate voltage which was for a max 6 DB overloading emergency uses of the naval ship uses. This means that it was safe for 80K Volts operational loads. This had happened back in the middle 1960s. Today the use of tube radios are almost not found commonly as it was during the 20s through the 70s, Thank God! It is and will be totally rare just find said vanish to used in the common workshop! sorry if this sounds a little angry but really I'm not even a little bit but it did drove me for loops until I Found-out the events and had some radio self works in Radio transmitters. Otherwise, I would have been totally lost.
Excellent video on testing spark plugs. Also, if the base of the ceramic part of the plug is burnt(brown around the part where ceramic meets metal), that usually indicates carbon leakage (bad plug).
I was given a Honda Harmony 2 with a bad plug. It ran, but ran terribly. As soon as I replaced the plug, it ran great. Thankyou friend that gave me a free mower. My point is, change the plug if you are experiencing issues that make no sence. Sometimes the plug works, but it may be badly worn or thermally destroyed. If the center electrode is cracked, you cannot see that. Heat and age can and does break down a plug. NGK sparkplugs that are normally in Honda mowers are known for fouling issues over time. I should know. I have had years of experience working with them on snowmobiles and motorcycles.
Good to know; thanks Steve. Funny though. I have worked on many dozens of old & newer small engines since 2011 & never had to buy a new plug. I think replacing the plug annually or running out to buy a new one as soon as an engine becomes hard to start (usually fuel related) is a waste. Champion & NGK must love it though!
Running out to buy a new plug maybe justified only in situation when you first received a small engine, and it would not start, you narrow down the reason to the freaking thing just won't produce sparks, and it's cunt of thing to take the whole thing apart just to be able to check all possible points of failure in the wiring etc. Provided everything else is equal, you really want to bet on maybe that ugly, no brand, not even straight sob of a chinesium of the chinesium spark plug may be the cause. If it doesn't look right, it usually isn't right. But you never know, you could run into the ugliest shitty looking sparkplug that defy beliefs to be a working one.
I rarely have to replace spark plugs in mowers... the mower i use now is a yardman 2004 with a 6.5 briggs...starts with one pull... i bought it used in 2013 i think the plug was just replaced...i never have taken plug out to even look at it... i never heard of a mower getting ruined by a bad spark plug... i change oil every 3 years. and keep air filter chean... i just cut/mulch my 1/2 acre or less yard maybe 25 times each year...No smoking or lack of power,runs strong... i think this 6.5 briggs is a very good engine imo..
I get free or cheap gas engine machines and i fix them and resell them if they are still good. I hear this all the time. I changed the plug and it still wouldn't run so I bought a new one. Actually it is almost always a dirty carb but I rarely have to trouble shoot a spark plug. i did not know how to test them though so thanks for the great video. now I can make sure the plugs are working properly in machines I sell.
As always good tip One trouble is the multimeter ohm meter is only 1.5 to 9 volts. May show open at that voltage but I'm the engine the spark gap sees thousands of volts and shorts before you can get a spark. Even if you use the out of the engine spark plug test when in the engine the compression of air may be enough to prevent the spark. The low voltage of the multimeter has fooled people in many other applications But your experience tells me to try this first. Thanks again 😅
I had a pressure washer (with a Honda engine) that started fine and ran fine for exactly 20 seconds and then die. Start right back up, run for 20 seconds and die. After rebuilding the carb and replacing the fuel pump to no avail, I decided to pull the spark plug. It looked fine. Wasn't fouled or worn out. It was a resistor type plug. Checked the resistance and it was spot on. Reinstalled the same plug after cleaning it and the problem remained. Decided to replace the plug anyway and that fixed the problem. Moral of the story, a plug that bench-checks good may in fact be bad and the cause of your problem. Obviously, the plug had some type of defect that would cause it to fail after temperature (and/or pressure) reached a certain level causing the plug to malfunction and the engine to shutdown.
Hello Steve. Greetings from Cheshire, England. First of all, I want to thank you for putting out these excellent videos and sharing your knowledge. They have helped me and my son to refurbish and get running well several old and knackered ebay chainsaws since Buckin' Billy Ray got us hooked on the subject (seems there's a bit of a BC influence going on here: maybe we should visit some time). Now to business. Pulled our old neglected Honda GCV160 powered lawnmower out of its winter storage in the log store on Friday. Started no problem then died after about 30 seconds and would not run again until left for a good while. Did this a few times. Suspected fuel starvation. We obviously had a spark. Spent the weekend doing all the following in accordance with your videos with no change to the problem, as well as cleaning the spark plug several times along the way (carbon fouling). I tried: purging and adding fresh fuel (turns out my younger son who loves mowing had filled it with 2-stroke mix while I wasn't watching), running without fuel cap, running without air filter, cleaned air filter anyway, dismantled and cleaned carb (didn't look too bad but it's sparkly now (a one bottle of Les Dauphins Côtes du Rhônes Villages job), checked remote choke operation (not auto choke) , checked fuel supply to carb (no problem: shut the fuel tap immediately it cut out and drained the carb bowl a couple of times: it was full (and no water)), reset the valve clearances (inlet was spot on but exhaust was at 15 thou. (nearly a full bottle of Marqués de Montino Rioja job)). No change. Finally the new spark plug (Bosch WR8DC - equivalent to NGK BPR5ES as specified in the Honda engine manual) arrived. This was a desperate last chance to save the mower from the tip as we obviously had a spark. I put it in and she now runs perfectly. £5 plug saves £400 on a new mower. The old plug (NGKBPR6ES) tested out okay with my multimeter according to this video: no short circuit between centre electrode and ground and 4 kOhm on the centre electrode. So it seems the plug was failing but only when it got warm. Have you ever seen this sort of failure before? Thanks again for all your help over the last couple of years. Best regards and keep on rockin' in the free world, Dave.
Great vid Steve technically you should use a megger (which is a ohm meter that uses high voltage) to test the ceramic insulator because sometimes the insulation in this case (the hairline crack in the ceramic) will not leak at low voltages (your volt ohm meter likely has 9V battery) the coil of your small engine produces thousands of volts so the plug could leak at the higher voltage produced by the coil but test fine at the lower voltage of an ohm meter of course no one watching this video can afford a megger except an HVAC tech.
Thanks for the vid Steve. I once had a problem with a saw that wouldn't start. It had fuel, spark and compression. After checking for spark as I went to install the plug I noticed the center electrode move and slide down until it contacted the ground electrode. When I flipped the plug back to electrode up it slid back showing the proper gap and would give a spark. So while it looked good and passed the spark test, when installed the electrode would move and there would be no gap. I tossed it into the garbage can!
Good info Steve. I think I had one like the last the other day. Tested it for continuity and spark, which was all good, but installed in the head, it would try to kick off and die. I think the compression was separating the inner electrode. Switched out the plug, and the engine ran like a champ. Was weird for me, first time Ive ever encountered that. Keep up the good work.
Dang....talk about spark plugs. Just worked on a Troy Built 105 140cc MTD for a relative. Pulled the plug and left it connected to the coil wire and was getting fire through the spark plug when turning the engine with a drill. (I had already eliminated the possibility of it being a fuel issue.) I'm now thinking timing like crankshaft sheer key issue.....it was perfect. I reset ignition coil gap while I was at it and still could not get it to fire....along comes this video and bingo....I tried a used compatible plug that was in my tiller and the thing runs like a champ. The spark plug was getting spark but there was some issue with the internal electrode that cause the ohm reading to read no continuity when testing it? PS...Coors Light is my go to beer so this video was extra special..lol ! Thanks for you videos.
Great video Steve as always! My understanding is that resistor plugs are to eliminate interference with electronics? If so, why do small engine manufacturers list both resistor and regular plugs for their engines? I don't see a whole lot ( if any) electronics on most small engines. Thanks
Many small engines have a CDI ignition system (Capacitor-Discharge Ignition) which is sensitive to electrical noise. You can use a resistor plug in any type of ignition, but you can only use a non-resistor plug in a solid state ignition system. Resistor plugs are far more common than non-resistor plugs, and I’m sure many small engine manufacturers list a resistor plug for the sake of commonality. Non-resistor plugs are unnecessary and obsolete.
Totally agree that we need to repair, Not just replace. While it may be easier to just switch out, it’s not effective diagnostic testing. I want to know what the problem is and why…..this test does that for me. Thanks.
Great video. Valuable info for sure. When I was a kid,before we had cable tv we had an outdoor antenna.whenever a snowmobile went past the house that didn’t have resistor spark plugs in it the picture on the tv would get fuzzy until the snowmobile got a ways down the road. Please keep the videos coming
I appreciate your explanation on checking spark plugs. I’ve probably thrown a lot of good plugs away not knowing the proper way to check them. Hopefully this will save me some time and money! Thanks again!
Steve, you are the best. Even though I have many years of experience in both electronic and automobile services, I still learn a lot from you regarding the correct resistance for a small engine spark plug. I will watch your videos from now on, there is many things that I don’t have knowledge of, big thanks.
I've watched this man's video's for several possible problems and troubleshooting points and the possible causes...I am never disappointed...I only wish I could pop a top or two with him.
The other good reason to know how to do this is faulty new plugs. That has happened to me in the past. Sent me off on a wild goose chase. Keep on keeping on. Happy New Years
I got a flute multimeter picked up at a yard sale for $25 best deal I got that year about 5 years ago but I had one already not that brand Great videos
Nice video describing how to test a spark plug. I reacted to two things in this video, you are not doing it wrong. but i feel like adressing it. Not holding the tip of the mesuringprobes is good practice, but it does not affect the answer you will get at those readings. this is becouse the readout from hand to hand is approx 5 000 000 ohm. As for the insulation testing. A multimeter will normaly not be able to test with more than 2v. for a more trustworty insulation test it should be tested with an insulation tester with high voltage mesurement(electrician tool wich is to expencive to consider buying for the regular person). however testing it with a multimeter will show if it is totaly flawed.
Yes a megger would be better for checking the insulator, however a decent quality DMM can measure resistance to 50 mega ohm, your body resistance, which can be much lower than 5 meg if sweating, will seriously affect the reading. General all around good practice - don't touch the probes.
Another good article. One issue, though. If the insulator core is cracked, it will indeed most likely cause the spark to short circuit there. But that in itself may not cause your ohmmeter to show the problem, however, until it has gone on for some time and a carbon track has been created. I like to check my plug out of the motor with the wire attached and then pull the rope (in a relatively dark area), and look for the spark. Of course, under compression it is harder for the spark to be created, so there is still a remote possibility that it will spark when not in the engine but fail to spark when installed.
Very very helpful information. All your videos are real,I have tried them and they have helped me a lot.Lifesaver.👍.May The Lord God Almighty bless your family and your work.
great videos, way back in the 70's auto m. school we had a spark plug checker that would check the plug under engine compression ,you hooked it up to 120 volt and a air hose.worked very well,i have not seen one since.
I enjoy all your videos. My favorite part is drinking an ice cold one. Thanks Coach. We're working on two old chainsaws that still got a lot of work in them, and one weed eater. Carb work on all, and a new coil on one chainsaw. The smaller older chainsaw, the coil measured no continuity. My question is, what burns out these ignition coils on small engines? Is it the heat or just too much use? I can't see any physical damage to the coil, so I imagine the copper coils just burned out. The repair was inexpensive.
I hope you don't mind if I add that many times a plug will check good on the bench but when it gets hot in the machine will fail. I know a lot of guys that will experience that and immediately shift their thinking to a carb problem when in actuality it is a faulty plug after all. Thanks for the video. I really enjoy watching your stuff.
I am an elec tech and can say Mastercraft meters are a great value. They are robust. I worked on ladders a lot. Every now and then my Mastercraft would fall. No problem at all.
I'm a tech too my Mastercraft let me down a couple times.. Might be robust but every once in a while I get incorrect readings... Changed the probes, didn't help, I don't trust it now.. I used to bring it places I didn't want to bring my Fluke but not anymore...
I'll just add that carbon (deposits) on the spark plug are conductive, they are resistive in nature, but they still conduct. Your ohm measurement number will increase the more carbon is on the discharge tip. Using a brass brush to clean the tip before testing would be helpful.
Excellent simple and clear instruction. Thanks you far all of your content. You present in a very simple and uncomplicated fashion. You are an excellent trainer / instructor.
What I have found works is taking a old push button grill igniter, splicing with an old plug wire and hitting the igniter. So far it's been working for me, on small engines at least
yes, thanks to you i just found out i have a bad spark plug, it is reading 0.011,7, thank you so much and the numbers keep jumping all over the place as well :0 my spark plus is a F7TC, no R in it and this lawn mower was shipped to me with a bad spark plug as a new mower :0 This lawn mower would start, but man was it a very hard start all the time ok :0
Steve's Small Engine Saloon Bill & Steve: As a guy who’s had a number of pacemakers for u20 some years, I’ve been told not to do any kind of electrical welding and stay away from strong magnet fields - like those generated by MRI machines. I’ll give Medtronic (the maker of my current (poor choice of words) and past pacemakers and see what they have to say. I’ll get back to you, Bill and Steve. Roy Lewis Buffalo, NY
Yes. You are definitely right. Next time when you see any electrical appliance make sure you add a resistor of some kind in the circuit. That way you can be sure that no one with a pacemaker, bionic eyes, ears, arms and legs is endangered by your use of any household appliances. The simplest to add a ton of resistance is to replace the electric wires in the power cable with very fine steel wire, like about hair thin. Its very cheap and effective, you can be sure it draw tons of voltages and that is good, that's what a good resistor is for. And don't you worry about the energy loss through heat, it's winter. Right. And I can guarantee you that you will not have to worry about it showing up in your next electricity bill if you follow my suggestion to the letter.
Very instructive walk around spark problems, thanks Steve! I'd like to widen your multimeter's application in the matter, and discovered INTERESTING symptom = the central electrode gains resistance during its work-hours! When you try resistance of new plug it's ZERO and audio-signal buzz loudly. After several w.hours you can't hear any buzz, but the meter shows abt. 1700mV drop on central el., yet no ohm res. It'd be interesting how a drop of conductance of centr.el. describes plug quality. My tests have been made on three plugs of various makes&wears. Namely: Champion/new ; Bosch/10hrs wear; Autolite/50hrs wear. The last one gives the poorest spark and is rather an exhibit now.
You scored a bullseye in my books Steve on the spark plug toss , you managed to miss all the beer bottles on the shelf behind you, sweet. Thanks for all your research you do for all your videos. 🍻👍
I have had many Champion Spark Plugs fail but no NGK.I find the spark travels around on the Carbon build up most times & a wire brush is enough to fix them.My Motobecane Moped 2 stroke was bad for that.
I agree Steve, Coors Light is excellent if you like a light beer, which I do,keep up the great help videos. I'm learning so much from your knowledge here in North Carolina 👍🏻👍🏻👣👣
Well presented and informative. I would add that testing between the centre electrode and the earth screw thread. Should be an insulation resistance test. This would highlight a breakdown in insulation not picked up a continuity test. I know I got over the top but thought I put it out there.
have bought new spark plugs that were DOA...of course didn't know that...and tell you what ... the old multi-meter will go to the parts store from now on...have gotten home to find the plug in the box was used too. thanks for the heads up.
Thanks once again Steve, very helpful. My multimeter has the dial, I set it to 20K, it gives readings to two decimal points. You mentioend that some people say that a plug is no good if it reads over 5 but that is not true with small engines. I tried a few NGK BMR79As, one that was in a saw, two brand new. They were all in the 9s, highest was 9.81 that came out of the saw, the new ones were both right around 9.5.
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Fix Stripped Spark Plug Threads For Free With This Hack ➜ ua-cam.com/video/yY_fuDRltZE/v-deo.html
How To Diagnose and Read the Color of Your Spark Plug ➜ ua-cam.com/video/Tz4uxFMUCOA/v-deo.html
Check For Spark On A Mower, Chain Saw or Other Engines ➜ ua-cam.com/video/VZ8r7xv3DLY/v-deo.html
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The resistor is there to suppress radio frequency noise which helps protect car radios, mobile phones and engine management systems. AND some ignition modules require a resistor plug to allow the coil timings to work properly.....
Old mechanic once told me to test a questionable spark plug you must first fill a 5 gallon bucket of water, then you must toss the spark plug in the 5 gallon bucket of water, finally observe the spark plug. He then said, "if it sinks then it's bad. Replace it." ;)
Your friend must of been a Navy man
I made spark plugs for 10 years, every brand you can name. Don't believe the bs that one plug brand is better than the other.
@@Weeble_Warbles your friend was crazy.
??? What??? Resistor for suppressing some noisy waveforms? You must be kidding! Chuck in a couple of ferrites will probably be of a better option if that is really your concern.
It's been a pleasure hanging out with you, Steve.
Thank You...
I just watched a guy test for spark at the spark plug of a mower that wouldn't run and had good spark, and from that moment on he tore into that mower to try getting it started but failed. As a last resort, he installed another spark plug and the mower cranked over and ran good. I did a similar thing testing for power at a washer machine with a neon test lamp, it illuminated and I starting tearing into that washer when I had a though, go out and buy a multi meter. I got home and the multi-meter and the 120V receptacle only showed 90 volts. I followed the wiring back to a junction box, removed the cover, and found a poor splice connection. I re tightened the splice connection, soldiered it, and got the 120V for the washer. You can't beat experience. I enjoy your channel, thanks for sharing.
I'm giving you 5 Stars for your full explanations, detail, thoroughness & product placement. Keep up the good work....
Thanks, will do!
Completely agree
i'm giving him 5 stars for the coors light on the table.
Thanks for this Steve. Keep them coming.
I'm now single after 30 years and never did anything like this, plus I lived in a major City. After moving to a rural location and needing chainsaws, log splitters, etc, your clear, concise videos are a big help in keeping them running and diagnosing when they aren't.
It's a 3 hour round trip to get a spark plug and You have to order them first.
Repairs are also stupidly expensive even for simple things and it's nice to know whether you are being told truthfully What's wrong, not just have parts replaced to bump the cost.
I've found a woman on her own can run into that sometimes.
You're Welcome...
MrsGraphiteGal
Another quick tip on a chainsaw or other motor, if it is not starting a quick check after trying the choke, and the regular starting instructions. Take out the spark plug to see if it is "bone dry", means there is NO fuel getting into the combustion chamber.Likewise if the electrode part is wet with gas, then you know it is gas fouled-won't run. At least you can know right away what is going on in there right quick if you are far from the shop or far from town etc. Good luck and Smart gal reading and watching this stuff. Also good practice to set your chain brake before trying to start- a sharp chain can cut you when it is not rotating, but not as badly as when it is moving fast.
Thanks Keith. I'm adding to my knowledge every day. Luckily my grandad was a master carpenter and my dad an engineer in the Royal Navy, I think I've inherited some of their creative abilities.
Don't worry, I am VERY careful with the chainsaw, never use it without at least trousers and gloves even when diagnosing it for a few minutes. Although, the guy who services it says not to use the brake when starting as newer chainsaws don't need it and it actually causes problems with the huskies. I still use it, if rather replace a part than my limbs !!
In High School Auto Shop we had a spark plug tester. You screw the plug into a small air chamber with a window on it. You add current and you can see the plug begins to arc.....but as you add air pressure (compression) a bad plug begins to stutter and fail under compression. That was a learning moment for me.
You know, that’s an excellent point that I haven’t thought of in 40 years. Thanks a lot.
@@NMranchhand I'm 61 now.... I've messed with engines since I was about 13...when your dirt bike keeps fouling plugs (or other things)..... it's either fix it or push it....so you learn to work on things. But yes...this fact still makes me wonder how compression effects spark. ua-cam.com/video/pl24m9utZLo/v-deo.html
@@readmore3634a cleaned plug will fire a dirty plug will fail the spark takes the path of lest res. (dirty plug) carbon build u on the porclin post bottom of plug its easyer to flow thru the carbon on that post to ground that jump across a gap so it fails --clean the plug no fail
@@frankdavidson9675
Thanks for pointing out the obvious. Why is it less likely to fire under increased compression?
Thanks Steve! Great information. My Pressure washer would not start. After watching this video I checked, and replaced, the spark plug. Starts easily now. Total cost $3.71!
You're Welcome...
Steve, thanks for the spark plug video. I asked several people about a spark plug tester. They said there was not one. Saw your video, and brought a multimeter. Sure beats putting in a new spark plug when the old one is still good. Thanks for saving me money!!!
Glad to help
The old days it was a screw driver but you could just hold it and pull lol
I'm in my fifties now, and I've owned multi-tester meters ever since I was a teenager --- you are absolutely right; even just a simple "no frills" unit is a total life-saver in sooooo many circumstances, such as when you're checking for the presence/level of voltage/current, testing for wire-breaks/shorts, etc.
I recommend better than “no frills” because my USA made fluke was able to find continuity issues in 3 resisters on a Deere mower OSHA safety board (ignition, seat switch, blade-PTO). Sent it to TV repairman who said the resisters were fine using his own Chinese(Communist PRC) multimeter. He was wrong, My fluke was right. Diesel motor had vibrated the wire ends of the resisters to form cracks.
@@hugoglenn9741 Yes, the cheapie ones do tend to break down after a fairly-short time. Even the costlier-model Micronta testers from Radio Shack didn't last --- they suffered worn-away rotary-switch contacts, just like the bargain-bin-grade meters often do.
Hey Steve, I had a beer with you watching your video!!! I learned something today! Only after 50yrs. being a car and ambulance mechanic! I'm learning more and more how to keep the small engines running on my lawn tractor, weed wacker, chain saw, etc. HOW DOES THE OLD SAYING GO, YOUR NEVER TOO OLD TO LEARN SOMETHING NEW!!!! THANKS STEVE!!!
Right on buddy!
When I was a VW mechanic back in the sixty, we has a spark plug tester. You cleaned the plug first, check gap, place in tester, some worked fine until you put 120 psi and no spark, a lot of plugs work fine until you put them under compression pressures and then no workie! My two cents worth.
Ive had that. Mower wouldn't start. Tested for spark with the spark plug on the engine casing. Sparked ok. Put back in and engine wouldn't start? Eventually tried another spark plug and the engine ran. It took me about an hour to figure it out plus a lot of swearing!
100%
Paul P how to does it work ???
This is so true. Your 2 cents are needed to buy new plugs lol
Yes! My father was an old time mechanic, and he had a spark plug tester. When I was a kid learning about cars, he demonstrated how a spark plug could spark fine at low pressure, but fail at high pressure. I couldn't believe it when I saw it. I couldn't believe why pressure would make any difference, but it did. It's something I never forgot.
Greetings from TEXAS. The resistor plug in the automotive industry is to help on Radio Frequency Interference for computers and of course the good time radio.
EVERYONE KNOWS THAT THE ''R '' IS FOR RADIO FREQUUENCE INTERFERENCE... if you do not know that then you are uneducated and need to go back to school...
I can remember hearing the engine noise thru my 8 track with regular plugs and solid wires 😂😂😂
I had an issue with my mower yesterday, I watched several videos but I couldnt solve it. Watching Steve solved lot of my issues also got to learn how to fix my mower. Thank You Sir!
Great to hear!
Love your work. Dont ever quit. Your making this world a better place.
Wow, thank you
QGreat show . For 50 years I had no idea how to properly and easily test a spark plug. Thanks guy and my next bee is in your honor
Glad it helped
I had a lawn mower given to me last summer and that was the only thing wrong with it. It was a Honda with an NGK. Those plugs are prone to foul out if the carburetor was been flooding. I used to buy a case of them every winter for my snowmobiles. I always carried extras in my pockets for my buddys. They NEVER had spares on long runs. On older snowmobiles, it was normal to have carb issues. Good video. I wish more guys would just go out and buy a spare plug for all their small engines. Especially chain saws.
RC Hobbyist Extreme same here how’s quarantine
....very worthwhile video. I'd waited till it was dark to test for sparks on the plugs for several old machines or even old new cheap machines I never touched in years. I had a few suspicions, you've pointed out defiinet things to check through. The clincher is some spark plugs have a resistance and 5k is actually a lot . I couldn't understand why all of a sudden one machine no longer showed a healthy spark . I'd been interchanging plugs on the machines . Fancy that , the Dickens you say , never knew plugs could have resistance .
As always, an awesome video and GREAT ADVICE Steve! Whether the others know it or not, all your videos are actually teaching people HOW to troubleshoot and that there is a proper progression to follow... (ie: not just jumping into throwing out the existing plug without checking IF its causing the problem) I was taught that from my (electrician) father over 50 yrs ago, I continue to (try?) and teach that to my sons to this day, but they’re all part of the ‘instant gratification’ society and, like on their video games, want to hit a reset button. To them, the time to just put in a new part... is ‘quicker’. Ask my 30 yr old son that now after buying a new battery for his truck, replacing the starter, THEN calling dad when it still wouldn’t start... Added 20 litres of gas, turn the key, VaRooom! Problem solved!
I agree about the kids and their video games.....I try to teach my 14 year old how to stuff and he gets impatient so fast... they're used to push button instant results.
Thank You... and couldn't agree more....
My uncle taught us to keep checking oil level and coolant when the engine is cold. It will tell you when its empty by no longer running.
WyrGuy2 iii
Haha... I'm trying to teach my 16 year old kid the same thing. Dear Lord give me patience.... why do these kids think that when I'm lookin n thinkin n not speaking.... it's NOT a cue to head back into the house and I'm to "text you when I figure it out"! Jeez! Pulling stunts like that will summon Momzilla....and that crazy lady won't tolerate a lazy smart ass. Even if I have no bloody damn clue what I'm doing!
I'm out here on a wing and a prayer with UA-cam videos and a stubborn ass personality. I hate to pay someone to do something I can learn to do myself. I'm a hard head but I'm finally fixing more things than I'm breaking further....so that's nice.
Yes Steve great advice. Was north of Inuvik and my chainsaw failed. No spare plug. Found out it was the coil shorting and used some grease from an axle bearing to run down the crack. Got the road opened and back to civilization!
Nice work!
I keep a neon sign transformer handy at my shop. 7,500 volts and low amps. With wires to a spark plug it simulates the ignition system voltage and a fouled out plug will sputter and smoke till the fuel burns off. Good for testing and if the ceramic isn't soaked with fuel the transformer will quickly clean up the plug to be able to use it.
Thanks for the "R" explanation. Makes sense after hearing it from you.
You're Welcome...
Ha i thought the "r" stood for racing
@@alanlake5220 same lol
Waist of time just use a screwdriver
Fantastic, as always. Thank you. Just a small note from an electronics guy: if the dielectric material (ceramic in this case) has a crack, the item which can leak between electrodes is current, not voltage. Love your channel.
Thank You...
Not entirely true. If there is a crack and it is not contaminated, the meter won't find it, but the high voltage coming through the spark plug wire will break down the air in the crack and act like a short. Kind of like a static discharge.
@@EngineerHank, then, there’s the compressed fuel/air mixture within the cylinder to which the energy has to overcome to cause ionization of that mixture. But, you already know this.
I tested a brand new kit of Magneti Marelli, 3 reading 5.4K and 1 reading 3.6K. I saw also the original technical manual of NGK and they infomed 3K to 7.5K as normal on resistive spark plugs.
Eliminating any potential cause is good. Knowing why a particular part failed is far better.
I dig your videos, man. Thank you for taking the time to share knowledge.
I appreciate that!
Just did battle with an old 8 hp Briggs L head for two weeks, new points and coil ( which were corroded and not producing spark), rebuilt carb etc... couldnt get it to run properly , was driving me crazy then watched this video and discovered bad spark plug. I should have known better, this video was a good reminder for me. Have one on me......
Right on
I'm still using your videos when I'm lecturing. You're great! I'm teaching tomorrow and using you and Billy Ray. You really help my boys. You teach really well, at their level. They're between 17-60. You're between saving them and bringing on the next generation. If you're ever in the UK we would love to see you. Thank you so much. p.s, I'll buy the beverage!
Right on Jo...
Mate you made my day!
I was testing the riding lawn mowers plugs because its engine was not having the right attitude. It was running, but once you clutch in the mower it did not have the torque it used to have. So I checked the plugs and, R-type, it was showing 4,7K on the one, 12,9 on the other plug. Voila! Problem solved. Thanks to your easy instructions on how to properly test spark plugs.Things can be so easy if you know what you're doing!
Thank You...and You're Welcome...
Good detail for the beginners. Thanks for this. A Lot of folks don't give ignition the respect it deserves. As a Master in the 70's spent a lot of hours keeping customers Eight-cylinder engines running strong on all eight. The good thing about a one -banger is, you always know when a cylinder is weak - because its the only one! -Sandy
Thank you. This just made my day
😅😅😅
I've got 16 spark plugs in my truck, at least 8 others between my small engine stuff so this is a nifty diagnostic tool, thank you.
You're Welcome...
Your videos are great Steve. Thanks for sharing you experience and knowledge. I wanted to share something that I think is relevant to this video. Just because a plug passes the test you outlined in this video does not mean the spark plug is in "good working order". I just replaced a BPR6ES in a mower with a GCV160. The mower would start relatively easy but after about 30 seconds it would die out. I was thinking carburetor\fuel issue but quickly ruled that out. Compression was 90+ psi with decompresor so wasn't too worried about that. The mower had good spark and the plug passed your test, 4850 ohms, and no continuity on the threads\body. The plug had pretty heavy carbon deposits that I cleaned away prior to the test. I replaced the plug anyways and my issue was cured 100%. So the question becomes...were the carbon deposits to blame? If I cleaned the existing plug and reinstalled it would it likely work just fine?
The correct gap is important . I just had a Briggs & Stratton 7 H.P. that would not run . The gap was .025 . I set it to the correct gap of .030 . It started on the first pull . Thanks for the information .
Helpful info, but for all non-resistive type of plugs, you will find that your multimeter will not be able to detect a crack in the porcelain insulator inside the body of the spark plug. The spark will jump across that point and also possibly the spark plug as well gap due to the high voltage of the ignition system (depends on where the crack is) but the spark may be very "weak" at the spark plug gap. Your multimeter on the other hand works on very small voltage for continuity and testing resistance so it will not be able to detect the crack in the insulator and as such the multimeter will read open or infinite resistance even though your spark plug insulator may be cracked. There is a case where carbon may build up inside the gap and short out the center conductor to the outside case. In this instance you will see a high resistance reading but it will not be infinite on your multimeter. For resistor type of plugs, these scenarios are also true, however you need to consider the 4.7 K ohm resistor in your measurements. Hope this helps.
If you have a crack in plug you will see it ark once the light is dim no need for mutimeter waist of time
Dale, you are 100% correct. I was going to point that out but did an F3 first and there you are. Thank you.
Good checks and ideas.
I saw a guy being neighborly and helping his neighbors with their mower doing prelim tests.
He couldn't see the arc of the plug clearly from pulling with it facing away and could see spark.
He continued and found lots of marginal issues.
He fixed each one or improved it spending time and materials on each aspect of good ability to run, basically refurbishing their whole machine.
When he was through, he was a-pullin and a- cursin.
His spark would rather arc to the outer circle (to ground) than jump the gap from center electrode to side electrode.
He did closer spark testing and got a good look.
Then he did what you said. Grabbed a plug from another and fired it right up
Cost him a Saturday and a Sunday instead of a plug.
Plus a plug , after.
No charge.
Nice guys finish last sometimes, but all his refurbishing, debatably, Did his neighbors machine some good. And the you tube audience was entertained if you saw what some of us saw right off.
My engine did not run because I forgot to open a beer.
Is that your medication 😅!!
@@uplift56 Beer is fuel.
Very common mistake that 😊
Steve, you are right. I am not in this line of business and I don't have a good spare plug sitting around. I need your method to get a yeah or nah of my current plug. Thanks much.
Glad to help
When I do my pre-season "Get-er-ready" routine, I pull the plug, wire brush it, lightly file it, and re-gap it. I have a 27 year old Honda 8hp Snowblower with the original plug. Do you thing I've gotten my moneys worth out of it yet. I have other 20+ year old engines that I've done the same. Good spark plug toss and thanks for sharing your vast knowledge.
I thought I was the only person that did that. I'll always try and clean it first before buying a new one unless I'm doing a complete tuneup
I sand blast mine
Hey Steve, if I may call you Steve, otherwise sorry, I had gotten one and only one that tested good by both tests, it turned out to be and well-insulated spark plug threads the fix was to PB blaster and then tap out the threads with anew spark plug tap. this clean out the threads to make a connection with the cylinder head I asked the owner what he had done had taped the spark plug outside and wet brushed the cylinder head with a radio vanish that he had found on his grandfathers' workshop and had seen how sharp his grandfather lawnmower looked. he was thinking that the old man just cleaned and then varnished those lawn equipment. but the spark plug was loose and the varnish just sucked its way into and between the inside threads and the outside threads of the spark plug luck would have the varnish was for 20K Volts transmitter plate voltage which was for a max 6 DB overloading emergency uses of the naval ship uses. This means that it was safe for 80K Volts operational loads. This had happened back in the middle 1960s. Today the use of tube radios are almost not found commonly as it was during the 20s through the 70s, Thank God! It is and will be totally rare just find said vanish to used in the common workshop! sorry if this sounds a little angry but really I'm not even a little bit but it did drove me for loops until I Found-out the events and had some radio self works in Radio transmitters. Otherwise, I would have been totally lost.
Excellent video on testing spark plugs. Also, if the base of the ceramic part of the plug is burnt(brown around the part where ceramic meets metal), that usually indicates carbon leakage (bad plug).
I was given a Honda Harmony 2 with a bad plug. It ran, but ran terribly. As soon as I replaced the plug, it ran great. Thankyou friend that gave me a free mower. My point is, change the plug if you are experiencing issues that make no sence. Sometimes the plug works, but it may be badly worn or thermally destroyed. If the center electrode is cracked, you cannot see that. Heat and age can and does break down a plug. NGK sparkplugs that are normally in Honda mowers are known for fouling issues over time. I should know. I have had years of experience working with them on snowmobiles and motorcycles.
Good to know; thanks Steve. Funny though. I have worked on many dozens of old & newer small engines since 2011 & never had to buy a new plug. I think replacing the plug annually or running out to buy a new one as soon as an engine becomes hard to start (usually fuel related) is a waste. Champion & NGK must love it though!
I agree....
Running out to buy a new plug maybe justified only in situation when you first received a small engine, and it would not start, you narrow down the reason to the freaking thing just won't produce sparks, and it's cunt of thing to take the whole thing apart just to be able to check all possible points of failure in the wiring etc. Provided everything else is equal, you really want to bet on maybe that ugly, no brand, not even straight sob of a chinesium of the chinesium spark plug may be the cause. If it doesn't look right, it usually isn't right. But you never know, you could run into the ugliest shitty looking sparkplug that defy beliefs to be a working one.
I rarely have to replace spark plugs in mowers... the mower i use now is a yardman 2004 with a 6.5 briggs...starts with one pull... i bought it used in 2013 i think the plug was just replaced...i never have taken plug out to even look at it... i never heard of a mower getting ruined by a bad spark plug... i change oil every 3 years. and keep air filter chean... i just cut/mulch my 1/2 acre or less yard maybe 25 times each year...No smoking or lack of power,runs strong... i think this 6.5 briggs is a very good engine imo..
I get free or cheap gas engine machines and i fix them and resell them if they are still good. I hear this all the time. I changed the plug and it still wouldn't run so I bought a new one. Actually it is almost always a dirty carb but I rarely have to trouble shoot a spark plug. i did not know how to test them though so thanks for the great video. now I can make sure the plugs are working properly in machines I sell.
Right on Buddy...
As always good tip
One trouble is the multimeter ohm meter is only 1.5 to 9 volts. May show open at that voltage but I'm the engine the spark gap sees thousands of volts and shorts before you can get a spark. Even if you use the out of the engine spark plug test when in the engine the compression of air may be enough to prevent the spark.
The low voltage of the multimeter has fooled people in many other applications
But your experience tells me to try this first. Thanks again 😅
Measuring eléctrical characteristic of the spark plug, I totally endorse that, thanks for taking the time to make this demonstration
You're Welcome...
I ate hamburgers on Wednesday
Hey Steve
I had a pressure washer (with a Honda engine) that started fine and ran fine for exactly 20 seconds and then die. Start right back up, run for 20 seconds and die. After rebuilding the carb and replacing the fuel pump to no avail, I decided to pull the spark plug. It looked fine. Wasn't fouled or worn out. It was a resistor type plug. Checked the resistance and it was spot on. Reinstalled the same plug after cleaning it and the problem remained. Decided to replace the plug anyway and that fixed the problem. Moral of the story, a plug that bench-checks good may in fact be bad and the cause of your problem. Obviously, the plug had some type of defect that would cause it to fail after temperature (and/or pressure) reached a certain level causing the plug to malfunction and the engine to shutdown.
Laid on the couch suffering from man flu and watching this Steve. Thanks buddy, feel better already!
Awesome...
Hello Steve. Greetings from Cheshire, England. First of all, I want to thank you for putting out these excellent videos and sharing your knowledge. They have helped me and my son to refurbish and get running well several old and knackered ebay chainsaws since Buckin' Billy Ray got us hooked on the subject (seems there's a bit of a BC influence going on here: maybe we should visit some time).
Now to business. Pulled our old neglected Honda GCV160 powered lawnmower out of its winter storage in the log store on Friday. Started no problem then died after about 30 seconds and would not run again until left for a good while. Did this a few times. Suspected fuel starvation. We obviously had a spark.
Spent the weekend doing all the following in accordance with your videos with no change to the problem, as well as cleaning the spark plug several times along the way (carbon fouling). I tried: purging and adding fresh fuel (turns out my younger son who loves mowing had filled it with 2-stroke mix while I wasn't watching), running without fuel cap, running without air filter, cleaned air filter anyway, dismantled and cleaned carb (didn't look too bad but it's sparkly now (a one bottle of Les Dauphins Côtes du Rhônes Villages job), checked remote choke operation (not auto choke) , checked fuel supply to carb (no problem: shut the fuel tap immediately it cut out and drained the carb bowl a couple of times: it was full (and no water)), reset the valve clearances (inlet was spot on but exhaust was at 15 thou. (nearly a full bottle of Marqués de Montino Rioja job)). No change.
Finally the new spark plug (Bosch WR8DC - equivalent to NGK BPR5ES as specified in the Honda engine manual) arrived. This was a desperate last chance to save the mower from the tip as we obviously had a spark. I put it in and she now runs perfectly. £5 plug saves £400 on a new mower. The old plug (NGKBPR6ES) tested out okay with my multimeter according to this video: no short circuit between centre electrode and ground and 4 kOhm on the centre electrode. So it seems the plug was failing but only when it got warm. Have you ever seen this sort of failure before?
Thanks again for all your help over the last couple of years.
Best regards and keep on rockin' in the free world,
Dave.
Great vid Steve technically you should use a megger (which is a ohm meter that uses high voltage) to test the ceramic insulator because sometimes the insulation in this case (the hairline crack in the ceramic) will not leak at low voltages (your volt ohm meter likely has 9V battery) the coil of your small engine produces thousands of volts so the plug could leak at the higher voltage produced by the coil but test fine at the lower voltage of an ohm meter of course no one watching this video can afford a megger except an HVAC tech.
I think it would be overkill. It's a very expensive tool if you only use it for checking leakage on a a sparkplug.
That's what the last sentence of my comment says
@@phillipcoiner4232 Then it's said two times. Just so we can get all with us, if they have any doubts.
Thanks for the vid Steve. I once had a problem with a saw that wouldn't start. It had fuel, spark and compression. After checking for spark as I went to install the plug I noticed the center electrode move and slide down until it contacted the ground electrode. When I flipped the plug back to electrode up it slid back showing the proper gap and would give a spark. So while it looked good and passed the spark test, when installed the electrode would move and there would be no gap. I tossed it into the garbage can!
Good info Steve. I think I had one like the last the other day. Tested it for continuity and spark, which was all good, but installed in the head, it would try to kick off and die. I think the compression was separating the inner electrode. Switched out the plug, and the engine ran like a champ. Was weird for me, first time Ive ever encountered that. Keep up the good work.
Dang....talk about spark plugs. Just worked on a Troy Built 105 140cc MTD for a relative. Pulled the plug and left it connected to the coil wire and was getting fire through the spark plug when turning the engine with a drill. (I had already eliminated the possibility of it being a fuel issue.) I'm now thinking timing like crankshaft sheer key issue.....it was perfect. I reset ignition coil gap while I was at it and still could not get it to fire....along comes this video and bingo....I tried a used compatible plug that was in my tiller and the thing runs like a champ. The spark plug was getting spark but there was some issue with the internal electrode that cause the ohm reading to read no continuity when testing it? PS...Coors Light is my go to beer so this video was extra special..lol ! Thanks for you videos.
Great video Steve as always! My understanding is that resistor plugs are to eliminate interference with electronics? If so, why do small engine manufacturers list both resistor and regular plugs for their engines? I don't see a whole lot ( if any) electronics on most small engines. Thanks
Many small engines have a CDI ignition system (Capacitor-Discharge Ignition) which is sensitive to electrical noise.
You can use a resistor plug in any type of ignition, but you can only use a non-resistor plug in a solid state ignition system. Resistor plugs are far more common than non-resistor plugs, and I’m sure many small engine manufacturers list a resistor plug for the sake of commonality. Non-resistor plugs are unnecessary and obsolete.
Totally agree that we need to repair, Not just replace. While it may be easier to just switch out, it’s not effective diagnostic testing. I want to know what the problem is and why…..this test does that for me. Thanks.
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Great video.
Valuable info for sure.
When I was a kid,before we had cable tv we had an outdoor antenna.whenever a snowmobile went past the house that didn’t have resistor spark plugs in it the picture on the tv would get fuzzy until the snowmobile got a ways down the road.
Please keep the videos coming
Thanks for sharing
Excellent video. So many people buy new spark plugs, when they could clean and reuse.
Right on ...
A very useful video, Steve. Thank you. I have often wondered how you could test the plug before replacing it. In the UK they range in price from £5-8.
Right on ...
I appreciate your explanation on checking spark plugs. I’ve probably thrown a lot of good plugs away not knowing the proper way to check them. Hopefully this will save me some time and money! Thanks again!
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Steve, you are the best. Even though I have many years of experience in both electronic and automobile services, I still learn a lot from you regarding the correct resistance for a small engine spark plug. I will watch your videos from now on, there is many things that I don’t have knowledge of, big thanks.
Glad to help
I've watched this man's video's for several possible problems and troubleshooting points and the possible causes...I am never disappointed...I only wish I could pop a top or two with him.
Right on Vern! Thank You...
The other good reason to know how to do this is faulty new plugs. That has happened to me in the past. Sent me off on a wild goose chase. Keep on keeping on. Happy New Years
Thank You...
I got a flute multimeter picked up at a yard sale for $25 best deal I got that year about 5 years ago but I had one already not that brand Great videos
Nice video describing how to test a spark plug. I reacted to two things in this video, you are not doing it wrong. but i feel like adressing it.
Not holding the tip of the mesuringprobes is good practice, but it does not affect the answer you will get at those readings. this is becouse the readout from hand to hand is approx 5 000 000 ohm.
As for the insulation testing. A multimeter will normaly not be able to test with more than 2v. for a more trustworty insulation test it should be tested with an insulation tester with high voltage mesurement(electrician tool wich is to expencive to consider buying for the regular person). however testing it with a multimeter will show if it is totaly flawed.
Thank You...
Yes a megger would be better for checking the insulator, however a decent quality DMM can measure resistance to 50 mega ohm, your body resistance, which can be much lower than 5 meg if sweating, will seriously affect the reading. General all around good practice - don't touch the probes.
Another good article. One issue, though. If the insulator core is cracked, it will indeed most likely cause the spark to short circuit there. But that in itself may not cause your ohmmeter to show the problem, however, until it has gone on for some time and a carbon track has been created. I like to check my plug out of the motor with the wire attached and then pull the rope (in a relatively dark area), and look for the spark. Of course, under compression it is harder for the spark to be created, so there is still a remote possibility that it will spark when not in the engine but fail to spark when installed.
Thanks for adding some Spark to my day muchly appreciated ! 😊
Our pleasure!
Very very helpful information. All your videos are real,I have tried them and they have helped me a lot.Lifesaver.👍.May The Lord God Almighty bless your family and your work.
Even if I already know how, I'll watch your videos because they are interesting, illuminating, and entertaining. Thanks for taking the time.
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great videos, way back in the 70's auto m. school we had a spark plug checker that would check the plug under engine compression ,you hooked it up to 120 volt and a air hose.worked very well,i have not seen one since.
COOL!
Steve your channel is the greatest, you are very informative with no Bull!!!
I appreciate that!
One of the best small engine mechanics that I've watched, excellent work
Wow, thanks!
I enjoy all your videos. My favorite part is drinking an ice cold one. Thanks Coach. We're working on two old chainsaws that still got a lot of work in them, and one weed eater. Carb work on all, and a new coil on one chainsaw. The smaller older chainsaw, the coil measured no continuity. My question is, what burns out these ignition coils on small engines? Is it the heat or just too much use? I can't see any physical damage to the coil, so I imagine the copper coils just burned out. The repair was inexpensive.
Nice job Steve. I recommend checking the plug when brand new as I have had brand new ones that are bad
Bring your multimeter when buying new ones. Had one read 8,000k right out of the box and tested the other one which was 500.
Buy ngk never had a bad one in 40 years champion on the other hand dont and wont use them rubbish
Hi Steve, you are my new Oprah. thanks for tips.
Welcome!
I’m hooked , you explain things so well.
Thank You...
I hope you don't mind if I add that many times a plug will check good on the bench but when it gets hot in the machine will fail. I know a lot of guys that will experience that and immediately shift their thinking to a carb problem when in actuality it is a faulty plug after all. Thanks for the video. I really enjoy watching your stuff.
I am an elec tech and can say Mastercraft meters are a great value.
They are robust. I worked on ladders a lot.
Every now and then my Mastercraft would fall.
No problem at all.
I'm a tech too my Mastercraft let me down a couple times.. Might be robust but every once in a while I get incorrect readings... Changed the probes, didn't help, I don't trust it now.. I used to bring it places I didn't want to bring my Fluke but not anymore...
Great way to check spark pugs and throw away the bad ones thank you
I'll just add that carbon (deposits) on the spark plug are conductive, they are resistive in nature, but they still conduct. Your ohm measurement number will increase the more carbon is on the discharge tip. Using a brass brush to clean the tip before testing would be helpful.
Great demo ! I'm testing my spark plug now
Excellent simple and clear instruction. Thanks you far all of your content. You present in a very simple and uncomplicated fashion. You are an excellent trainer / instructor.
I appreciate that!
Thanks Steve. Working my way through the possible causes of my saw not firing properly. It's a real education!
What I have found works is taking a old push button grill igniter, splicing with an old plug wire and hitting the igniter. So far it's been working for me, on small engines at least
Brilliant idea, I've got one from an old gas boiler. Thanks for that 👍
yes, thanks to you i just found out i have a bad spark plug, it is reading 0.011,7, thank you so much and the numbers keep jumping all over the place as well :0 my spark plus is a F7TC, no R in it and this lawn mower was shipped to me with a bad spark plug as a new mower :0 This lawn mower would start, but man was it a very hard start all the time ok :0
Great explanation. Wow, this can save you a headache. Thanks.
Thank You...and You're Welcome...
Thanks buddy it's never too old you're never too old to learn
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Thank you Steve some of us need all the help we can get when it comes to small engines
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Yes definitely so! I’m a class 8 truck mechanic and working on small engines is like walking on Mars,, the videos are great!
Great info saved myself 8 bucks
Good info Steve , I was told once that resistors also protect against interfering with cardiac pacemakers....could this be true?
Never heard that before but it sure sounds legitimate....
Steve's Small Engine Saloon
Bill & Steve: As a guy who’s had a number of pacemakers for u20 some years, I’ve been told not to do any kind of electrical welding and stay away from strong magnet fields - like those generated by MRI machines.
I’ll give Medtronic (the maker of my current (poor choice of words) and past pacemakers and see what they have to say. I’ll get back to you, Bill and Steve.
Roy Lewis
Buffalo, NY
Yes. You are definitely right. Next time when you see any electrical appliance make sure you add a resistor of some kind in the circuit. That way you can be sure that no one with a pacemaker, bionic eyes, ears, arms and legs is endangered by your use of any household appliances. The simplest to add a ton of resistance is to replace the electric wires in the power cable with very fine steel wire, like about hair thin. Its very cheap and effective, you can be sure it draw tons of voltages and that is good, that's what a good resistor is for. And don't you worry about the energy loss through heat, it's winter. Right. And I can guarantee you that you will not have to worry about it showing up in your next electricity bill if you follow my suggestion to the letter.
I read that in my mother’s pacemaker website manual so I can tell you for sure, yes it is true.
Very instructive walk around spark problems, thanks Steve! I'd like to widen your multimeter's application in the matter, and discovered INTERESTING symptom = the central electrode gains resistance during its work-hours! When you try resistance of new plug it's ZERO and audio-signal buzz loudly. After several w.hours you can't hear any buzz, but the meter shows abt. 1700mV drop on central el., yet no ohm res. It'd be interesting how a drop of conductance of centr.el. describes plug quality. My tests have been made on three plugs of various makes&wears. Namely: Champion/new ; Bosch/10hrs wear; Autolite/50hrs wear. The last one gives the poorest spark and is rather an exhibit now.
You scored a bullseye in my books Steve on the spark plug toss , you managed to miss all the beer bottles on the shelf behind you, sweet. Thanks for all your research you do for all your videos. 🍻👍
LOL. Right on Buddy...
That was risky behavior, come to think of it.
I have had many Champion Spark Plugs fail but no NGK.I find the spark travels around on the Carbon build up most times & a wire brush is enough to fix them.My Motobecane Moped 2 stroke was bad for that.
I agree Steve, Coors Light is excellent if you like a light beer, which I do,keep up the great help videos. I'm learning so much from your knowledge here in North Carolina 👍🏻👍🏻👣👣
Rock on!
Well presented and informative. I would add that testing between the centre electrode and the earth screw thread. Should be an insulation resistance test. This would highlight a breakdown in insulation not picked up a continuity test. I know I got over the top but thought I put it out there.
No this is a good test to do as it is surprising how many times you will find resistance doing that. I don't use those plugs.
Dale in Canada 🍁
thank you steve! Great video. yes i am one of the guys that might need this video, its a 45 min drive just to get to town, IF anything is still open!
You're Welcome...and Thank You...
You doing very good job 👍👍👍👍👍
Nice video 👌👌👌👌👌
You teaching very good you good teacher 👌👌👌👌👌
So nice of you
The thumbnail is amazing Steve!😂
Thank You...
have bought new spark plugs that were DOA...of course didn't know that...and tell you what ... the old multi-meter will go to the parts store from now on...have gotten home to find the plug in the box was used too. thanks for the heads up.
Does the color spark make a difference like a blue and orange spark
Yes it does, blue is best
Thanks once again Steve, very helpful. My multimeter has the dial, I set it to 20K, it gives readings to two decimal points. You mentioend that some people say that a plug is no good if it reads over 5 but that is not true with small engines. I tried a few NGK BMR79As, one that was in a saw, two brand new. They were all in the 9s, highest was 9.81 that came out of the saw, the new ones were both right around 9.5.
Good video I learn something new on every video you post thanks keep up the good work.
Thank You...
Thanks for clearing out the different between R(esistant) plug and the other.