2-Stroke Engine Only Runs on Choke (Will Not Run) This is why!
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- Опубліковано 12 лип 2024
- * VISUALLY EXPLAINED
When a chainsaw will only run on the choke position, it typically indicates an issue with the carburetor or fuel delivery system. The choke on a carburetor is designed to restrict the air supply to the engine, making the air-fuel mixture richer. This is necessary when starting a cold engine to ensure it gets enough fuel for a smooth ignition. However, once the engine warms up, it should be able to run with a leaner air-fuel mixture.
If the chainsaw can only run on the choke, it suggests that the engine is not getting enough fuel to sustain normal operation. This can be due to a clogged fuel line, a dirty carburetor, or problems with the fuel pump or diaphragm. The choke, in this case, compensates for the lean mixture by providing a richer mixture to keep the engine running, but it's not a sustainable solution.
To resolve this issue, it's important to diagnose the root cause of the fuel delivery problem. First, check for clogs in the fuel line and clean or replace it if necessary. Next, inspect the carburetor for dirt, debris, or gummed-up fuel. Cleaning or rebuilding the carburetor may be required.
Additionally, check the condition of the fuel filter, and replace it if it's clogged. Properly maintaining the fuel system ensures that the chainsaw receives the right fuel-air mixture, allowing it to run smoothly without relying on the choke position for operation.
If you want to see some great hands-on practical videos from a knowledgeable person, then take look at this channel. @RaleysSmallEngines
For some FREE Printable Download help Leaflets: www.therepairspecialistonline...
Timestamp:
0:29 - Engine Choke. How it works.
1:22 - Choke turned off. How the engine is working.
1:54 - Engine only runs on Choke. What causes this?
2:06 - Blocked Fuel Filter. How it causes engine failure.
3:20 - Fuel Tank Cap Breather. How it can fail causing engine problems.
5:00 - Simple Test. To see if Fuel Tank Breather failure is causing engine Bog down.
5:54 - Fuel Pipes. How they can cause engine failure.
7:37 - Fuel Blockage and how this effects the engine in detail.
8:56 - Carburetor Fixture and Fitting. Here's how a loose Carburetor causes engine failure.
12:14 - Carburetor Adjustment Screws. How the wrong setting can effects engine running.
15:04 - Metering Diaphragm Cap. Why this can cause engine Bog Down.
19:02 - Fuel Pump Diaphragm Cap. Why engine Bog Down can result from this.
19:53 - Fuel Pump Diaphragm. Here's how a defect in this can cause engine failure.
21:39 - Metering Diaphragm. This is how it can cause engine problems.
23:44 - A personal thank you to you. From Craig Kirkman of The Repair Specialist
So I have included how fuel filter blockage can reduce fuel flow through the carburetor, how the fuel tank cap breather system fails and reduces fuel flow, how fuel line blockage cap disrupt flow through and why a loose carburetor can cause bog down. Also, why failing inlet manifolds, carburetor adjustment screws, fuel pump diaphragms (caps and gaskets) and metering diaphragms (caps and gaskets) can all cause an engine to only run on choke.
This principle works for most types of Chainsaw saws, and the following also helps with Chainsaw maintenance. So, whether you are using a Stihl Chainsaw, Husquvarna Chainsaw, basically, all types of Petrol Chainsaw are valid for this principle, as well as many types of or a 2 Stroke Engine. The Electric Chainsaw, of course, escapes this whole principle!
Quality Carburetor Cleaner Spray: www.amazon.co.uk/gp/product/B...
Thank you very much indeed for visiting
Craig Kirkman (owner and creator of the Repair Specialist Channel) Please check out my amazon shop. I have recommended some useful items from Amazon below. I guarantee you that these items are the sorts of things I use on a daily basis so I know they are good. I have to be careful in recommending products because I have my name and credibility at stake. So I will only recommend good products. www.amazon.co.uk/shop/therepa...
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#EngineMixtureAdjustment - Авто та транспорт
All Episodes -for 2-Stroke Carburetors Here. Thanks. Craig:
ua-cam.com/play/PLrlXp3PlwgRI5OLvm3P91LJr1CYnO5TRD.html
This is gold for everyone like me, who has knowledge but not comprehensive. Now we have it all. I'm talking about whole series. My bow, Sir.
This is the best clearest and most comprehensive explanation of possible faults with a carburettor that I have listened to!
Well done and thankyou!
Thank you so much. It’s comments like yours that motivate me to continue making videos. Thanks again. Craig 👍👍👍
By far the goto channel for real diagnostic work on unsolvable problems you might face.
Best description of carb/fuel issues on UA-cam. It helped a lot of people and also made a few of small engine repairmen angry I’m sure. Thank you..
I dont think anybody out there can break down the circuitry the way you do. Nothing like being able to see in your minds eye whats going on. I have been able to troubleshoot so much better w all your teaching and circuitry breakdown. Just amazing.
Thank you so much for your nice feedback. It's comments like yours that motivate me to continue making these videos. Craig 😀👍
Wow, what a good explanation! Not only for choke issues but also for how a carb works in general.
One of the best videos I’ve ever seen! Thank you so much it has explained so much
You just save me huge headaches. Thanks so much. I didn’t even know my snow blower had a fuel adjustment screw. Fixed my problem without any tools. 👍
OMG thank you so much! Fix my backpack blower through the ol’ elimination process because of this video. My issue was leaking fuel lines. FIXED! 🛠
So very well done! Absolutely clear, concise and well shown. Couldn't imagine having it done any better. Cheers to an amazing job. Very much appreciated. Thank you!
Awesome Video.Everyone that works on engines should sit down and watch this.Thank's for sharing Your knowledge in a way that makes the whole fuel circuit easy to diagnose.
Best channel for small engines.
Thank you so much for your nice feedback. It's comments like yours that motivate me to continue making these videos. Craig 😀👍
This is one of the most comprehensive videos explaining Choke and issues related to fuel on UA-cam! - Well Done!
Thank you. I really appreciate your king feeeback. Craig 👍👍👍
THANKS FOR TAKING THE TIME TO GO INTO DETAIL ABOUT THIS TOPIC.
Very informative. I never really understood the process. Thank you very much for this knowledgeable video.
Thank you, you just made a small problem bigger. BUT in doing so you increased our understanding. Which I think is a good thing. You educate us and that is the best thing of all.
Another excellent video which clearly explains the majority, if not all of the 'fuel starvation/choke on' problems encountered with small engines. The only fun left now is work out which one of these issues you are having? 👍
Yes, Thank you for mentioning that. I should have included it in the video. Thanks again. Craig
Pretty much start at 1.....
Excellent information as always. Thank you Craig.
Had this problem with my small 2 stroke generator yesterday. Went through it after seeing this video, didn't actually see any issues, but after cleaning the system and tightening everything up, it now runs perfectly.
Thanks for your help.
Awesome. I’m pleased you sorted out the issue. Craig
I'm actually watching all of your applicable videos on two stroke engines because of my interest in flying 2 stroke engines on Paramotors. Not until today did I understand the low and high limit screws on my British made Parajet Maverick, that has an Italian 2 stroke engine made by Vittorazi. Oh by the way, your electrical explanation videos are great too.
Carburetors have always scared me because I never understood them. Until I have been watching your videos!🙂 Now I have more knowledge of carburetors and their workings!👍 Much thanks to you Sir!🙂
It's a Beautiful work, Master.
I feel like I've learned more useful information in this video than I did the whole time I was in school,,, very well done
Great stuff my brother thanks for your time and expertise!🙏🏻
watched a few of your videos and will watch more. good drawings to help understanding as well as good descriptions.
Bravo! Your time is greatly appreciated.
Of all the videos I have watched on this issue yours is the holy grail! Wish I had found it sooner...thank you!
Thank you for your awesome feedback, I really appreciate it. Craig 👍
Very good video. I have learnt alot. Thankyou very much. First time seeing 1 of your videos. And ofcourse I subscribed. Great job teaching us. Thankyou☺
Thank you for this amazing video. I'm dealing with this issue and I ignored the carb as a culprit since its barely a year old. I now know how to be very thorough in my testing. My God bless you and keep you.
Awesome thank you. Craig
Thanks for the video!
I had this problem, and after watching this video, I was able to pinpoint the problem. It was the metering diaphragm. It had become too stiff with time and it wasn't allowing the needle valve to come off its seat and allow sufficient fuel flow to the main jet after taking off the choke. Out of curiousity, I compared the new diaphragm to old diaphragm, and the new one was much more flexible.
I absolutely love the educative nature of your videos -- the theory, practicality, and reasons. Thank you!
Really thorough overview and in the order of operation. Best teaching video.
amazing video! keep up the great work
This finally happened to me with our chainsaw. Thank you so much for this wonderful knowledge and resources on this site
FROM ACROSS THE WATER, VERY WELL DONE MATE, THANK-YOU SO MUCH !!
Good morning Craig. Your videos are the very best how to's. You explain everything very clearly. I watch every one of your videos and learn something every time. Thanks for sharing.👍👍
Thank you so much for your nice feedback. It's comments like yours that motivate me to continue making these videos. Craig 😀👍
@@TheRepairSpecialist Well I say what I am thinking. Besides I heard that we Canadians are polite. 🍁😁
Great refresher for me. Used to race motorbikes forty years ago and had forgotten what I had forgotten if you know what I mean.
Nice simple early 2 stroke tech, love it. Keep up the good work.
Thank you so much. Craig
all vids are great and very helpful. i did notice one lack or i missed seeing it. it is how a def hi ck valve preven
ts purge bulb drawing in fuel and pushes out all fuel when in low speed. ck not closing on low circuit lets 14.7 lbs atmosphere pressure push into metering area pushing diaphragm away shutting off fuel supply and gradual starving down at low speed/idle and adding air to chamber and pushing all fuel out of purge bulb. with no ck /defective works good on hi speed and full choke starts ok 5-7 pulls like no purge bulb. engines. thanks for the great vids.
I always love your vids. You're very thorough with your explanation s. Thanks so much.
Yes, Thank you for mentioning that. I should have included it in the video. Thanks again. Craig
You win DIY youtube informational videos!! Excellently done Sir!!
Very informative, thank you
I think,one other problem could be that vacuum line(pipe) could be little cracked and fuel pump wont work very well and dont pump enough fuel.
Thank you very much for this detailed explanations.
THANKYOU FOR THE CLARITY AND CLEAR EXPLANATION '''MAGIC MAN'' CHEERS....
ANOTHER 10/10 VIDEO WELL DONE EAC
Great job as usual !
Thank you so much for the nice feedback. I really appreciate it. Craig
Thanks a lot for the video... it really help me to solve the problem that i was having (choke cable was not fitted properly and leaking/breathing through the cable seat. Thanks again :)
Superb and valuable vid, thanks.
Lead source of choke only idle. It was fuel shut off valve. 2 days of troubleshooting solved! Thank you!
Great job. Thank you!
Thank you! Very good video.
Extraordinary explanation and presentation!
Thank you so much :D really appreciate it :)
- Craig
Best Video on all carb issues
Thanks. for this.. Saw 👀 your channel just before I started stripping the carburettor down! Fuel filter was blocked! Working fine now!
Excellent Carb Presentation....
The Best of the Best.
Wow, thank you! I really appreciate it. Craig 👍👍👍
Your a legend mate, thankyou, really appreciated. 🇦🇺
this is a great video , very informative
Thank you so much for your nice feedback. It's comments like yours that motivate me to continue making these videos. Craig 😀👍
Thanks God for sharing your knowledge about this matter, very impressive and helpful.
Excellence in action here, mate. Perfect presentation, clear explanation, perhaps showing actual examples of each component would help the inexperienced viewers even more. Not a criticism, encouraging the excellent work you have done.
Thank you for this great explanation. I was having a hard time figuring out what is going on with my two stroke outboard and this has helped me identify the problem and fix it. :)
I enjoyed the video. Awesome explanation on all the parts and how they work.
Thank you. I appreciative your nice comment. Craig 👍
Awesome tutorial. Thanks for sharing.
Thank you so much. Craig 👍👍
Excellent video.
Thank you very good.My Evinrude thanks you too. Now we can go sailing👍
You are genius!! God bless you!! ❤
I really enjoyed that, I think I now have a rough idea as to why I can't get my lawnmower running. 👍
Thank you so much for the nice feedback. I really appreciate it. Craig
Thank you Sir, for the video.
Thank you for the shout out my friend.
Thank you to 👍👍👍
Excellent video it seems that you are a specialist as your name on this video, I had a problem with the manifold loose the 2 screws that connect to the carburetor but i noticed that the gasket is missing so this may be the problem.
Thank you
An excellent explanation of the malfunctions of this type of carburettor!
Maybe some advice about the fuel used.
NEVER use alcohol containing petrol, this will dissolve the rubbers of the membranes.
You can only see this clearly if you hold them up to a light.
You then see the fine grid of the fabric on which the rubber was attached.
These rubber particles contaminate the carburettor and all small holes need to be cleaned, sometimes very small ones.
Awesome, and Thank you.
Thank you too! I really appreciate your comment. Craig
Very good!
Excellent fluent presentation from one who knows machines.
Thank you. I really appreciate your nice feedback. Craig 👍
Good work mate
Great video. I had replaced the carb on my Echo trimmer and couldn't get it tuned. Watched the video and decided that maybe I should take it all apart and start fresh, thinking that maybe there was a leak somewhere. Took off the carb and even though I thought I still had the screws in far enough to hold the gasket, it was off on one side, hanging down. I continued checking tightness of everything and put it back together, making sure that the gasket was correct. Wet through setting it up from scratch again (idle speed, High and low needle valves) and had it running like new in a few minutes.
Thank you for the great explanation.
Thanks Fantastic. I'm really pleased it's up and running. Many thanks for your awesome feedback as well. Craig 👍👍👍
Great job grate video !!
Thank you so much for the nice feedback. I really appreciate it. Craig
Great video. So simply put , it's either a fuel blockage or air leakage.
Brilliant job and IMO the UK accent adds a bit of authority to the instruction!!
Again well done Thanks
Good video, working on my Strimmer engine right now, after many years of no use (because it wasn't working correctly), found several faults, partial fuel filter blockage, leaking fuel tube inside of fuel tank and air filter blockage. Ran it after rectifying the faults and found it working on partial choke quite well, will try it under load tomorrow. Was going to buy a new electric strimmer so if successful you will have saved me much needed money (Pensioner). Many thanks for your info.
I appreciate you sir. Thank you for sharing your skills knowledge and experience
Thank you so much for your appreciation and nice feedback. I really appreciate you. Thank you. Craig 👍
@@TheRepairSpecialist I checked the tank, I even bought another tank and was going to install it today. But I never tested the vent. I'm certain this is what's happening. The tank is warped kind like there was excess suction inside it like a gas can does in the cold. I don't know why it didn't occur to me sooner, I've even seen it suggested in other videos. I've been through the whole outboard at this point. It runs like a top until you open her up. That's gonna change today thanks to you sir. This old pontoon has a fuel fill and vent attached to a broken trim ring and they're all super weathered. I'll replace it all but for today I'll take your suggestion and leave the cap slightly loose. I can't wait for my family to wake up lol.
Your walk through on how all this stuff works and works together is the best on UA-cam. I'm grateful to have found your channel
Excellent!!!!!
Thank you! Cheers!
Likely the best run through of the causes of this problem on the web! And then there is a longer, more comprehensive "full" version too? I am onboard.
Thank you very much,I've learn something secret about caburator & H&L screw settings of fuel amount entering the chember
I found the problem is usually an air leak in an old fuel line, the solution is cut off the cracked end and reconnect. It could also be in an old tank where the tank take up hardens and expands. Replace the old parts or wrap teflon tape to make the take up plug in tighter.
Thank you!!
Quality 👍
Thank you so much for the nice feedback. I really appreciate it. Craig
Very nice video
great video .What about when chainsaw only idles on 3/4 choke. Could it be from the same things explained?
awesome explanation 👍cheers
Thats Totally Unreal I ONLY THOUGHT I KNEW About These Small Engines, But I Dident Know Squat
I've just dealt with my " the handy" strimmer. The beast kept dying off choke.
The fuel supply line had snapped. No vacuum equals no draw of fuel. Resulting in a dead cut.
Have this problem right now, 450 sthill. Thank you very much sir.
Thank you for your feedbck. I hope you got it running ok. Craig 👍
Excellent channel. My Stihl 600BR used to run well before a Stihl certified tune up. Now, it runs when the machine is warmed to room air, started and operated above 0 degrees C. At -30 degrees C, it starts and idles but bogs down as the throttle is advanced. I’m curious how to diagnose and fix this.
Hi, have a weird problem where line trimmer starts and runs and i can add more fuel or lean per the screws but after a period when hot, it wont idle anymore. Part choke saves it but it not happy engine!! Have switched carbs (3) and gravity fed fuel and even cut the pump vanes off and fed it fuel in case the pulse channel was dying after a period, but why would that happen? unless piston bore clearance and pressures suddenly drooped off. so cant be fuel delivery problem or vent valve as bypassed all that. Also i quickly checked for spark when it died and seemed to be still sparking but too weak when hot?
Could it be simply a weak coil thats dying when warm and spark not strong enough? Also one time after 15 mins it refused to go above half revs even when i pumped the throttle. Electronics in coil failing and restricting RPM? a few mins later it was back to full power and rev up down ect. I honestly thought this machine was haunted as intermittent running problem with plenty of juice available on start so good fuel and spark then but not good spark when warm?
Would part choke save a weak spark situation ? Also when after start, idle screw needs to be changed a bit, it wont lock on to one setting. Comp test was around 100psi. cold. Could the engine be bleeding off suction and pressure when hot as its old? . 3 carbs , 2 new and 3rd completely rebuilt on this machine of varying throat sizes but they all idle and fail the same after about 15 to 30 mins. same symptoms. Also pressure tested engine and got 9 lbs, no leaks but replaced all seals and crank seal in case they were bleeding when hot. So engine is air tight.
Baffling!!
thanks if you can help...
Id be trying a coil,,,,i know its easy to just say and throw that out there from a chair but i would try a new coil and spark plug. This is of course is figuring all of the other basics are good which sounds like you got covered (vacuum leaks, etc). Love to know what you find. Stay safe and good luck
Do you have a spark arrestor on that unit? Pull it and check it. If clogged, use a propane or mapp flame to char it and brush off the soot. Interesting problem. I'm gonna assume you fixed it or had it fixed. What was the problem?
@@alext8828 Hi, i found the problem. You need about 90 psi for 2 strokes to work and i was getting 100 cold but only 70-85 hot?? and thus it couldnt run but took 10-20 mins to get hot and bleed off. Caused by worn bore and rings. Put new rings and checked hot and back to about 100 but the piston the bore clearance ect is not good so this wont last too long and that will be that for this machine . Good learning experience and i had to work this out myself as engines are supposed to increase psi as they warm up not the opposite. 2 strokes are very picky as they have to compress and suck the mixture in, so clearances are very tight. Thanks for replying. all good now..
@@xx3868 Glad to hear it. BTW, ring clearance is the thing to watch. Piston clearance is secondary. I think you'll be fine for a long time. Good luck.
But what about a engine that only starts when holding the gas wide open like my chain saw?
Hello, I have a back pack stihl leaf blower Ive done all this stuff to this thing fresh fuel, tank vent good,new carb actually 2 carbs the last one is original eqip.Anyway same thing on bogging and sometimes wont start yet running good while chocked a little bit ,even better when i shake up the gas tank to give it more pressure.,,Crazy thing is when i open the gas cap it will then just die out..The muffler is clean the cylinder looks new no scoring only thing left I was thinking is the crank seals?what do you think? any suggestions? Thanks! B.
Ty sir…
Thank you for watching the vid. I really appreciate it. Craig 👍
Wow...very very well explained. Just what i need to fix my weed eater.... BUT my carb got only one screw,, just above where the inline fuel pipe connects with the carb... 🤦♂️ There is no H or L... 🤷♂️
Thank you for your nice feedback. Its very much appreciated. Take a look at this other video of mine, which explains the basics on single adjuster screw systems on carburetors. It might help make things a little clearer. Here it is: ua-cam.com/video/oDkVVL0CJqk/v-deo.html . Thanks. Craig
Oh small 2 strokes…. I have a collection of mixed Echo and Stihl, my diagnostic starts with throwing on a new carb and usually that solves my problem(s)