My Mercury 9.9 hp outboard, non electric start motor has the exact same carb on it as your 25 hp. I rebuilt it last year and haven't been able to start it. It wouldn't start before because the fuel diaphragm was totally messed up. I searched everywhere for video for 9.9 and nothing, then today, recommendations gives me your video. I gotta check that gasket to see if it too is blocked from fuel delivery. I can rebuild lawn mower motors all dang day and they fire right up. These outboards are a different story for me.
Thank you so much for mentioning that gasket slot. Might’ve just solved my problem. Was still acting like it wasn’t getting gas after a rebuild. I noticed that the new gasket didn’t have the slot but didn’t think twice about it
also be careful with the diameter of the gasket circular opening - on some kits, it is made for 20hp and smaller and not for 25hp which has significantly larger carb outflow opening (as on this video).
I have the exact same carbeurator. I have pulled it apart and cleaned everything and blasted air through every vent I can see. The motor runs for a few seconds if I spray a little gas straight into the carb, but will not run otherwise. The carb bowl is filling up. And when I saw you’re issue with the gasket, I thought I had it pegged. I’m stumped. Been working on this thing for over a week now.
I have some thoughts but I’m not an expert. How new are your spark plugs and did you gap them? When you put the carb back together, where did you set your air/fuel adjustment screw? Do you have the electronic choke? Do you have the “Pull to Prime” option? Is the vent on your fuel tank open and a working primer bulb? Fuel filter been cleaned/changed? And was the motor running at all before taking the carb off?
@@sirmarcusandrew Thanks for the video, very helpful. How do you set the air/fuel adjustment screw? I took the carb apart without paying close attention how far in that screw sits.
@@MarinusVesseur ua-cam.com/video/zm5mB3R8Ucw/v-deo.html See if this helps. I think I am around 3 turns or slightly over if i recall from where I set mine. Watch the last 10 minutes or so of this different video to help as well. ua-cam.com/video/Dnues7Np1Uc/v-deo.html
Great job and very helpful. When I put all back together it only starts with starting fluid. But once it starts it runs good. I have 03 25hp electric and pull start. Please help...
I just bough the carb kit, I was going to rebuild because the primer vent hole has fuel spurting out when I pump primer. Is that new diaphragm going to stop the fuel from spurting out???
Danny B it did on mine. I had a deteriorated primer and the debris blocked the holes and the pressure pushed the fuel out. I cleaned everything out and made sure all ports/holes were free of obstruction.
My friend just bought a boat with a 2003 25EL, OT690351 motor. I know I'll be helping him with it when the need arises, so I've been searching for information on it and your videos have been great. I hadn't realized it was a diaphragm carburetor, so that was good, and highlighting the problem with the gasket was noted. At 3:29 of your video you "reset" a screw with a lock nut on it, and mention fine tuning it later. What is the function of that screw? Thanks
It works in combo with a few things. It limits the return of the cold start arm as part of a minimum idle. Set too low (too much return) it will be hard to start and too little return it will rev high like you have the throttle opened too much. I’ll try and get a video made soon to discuss it.
Hey mate, thanks for a great walk through. New to the whole outboard scene and am trying to get a 15hp 1993 merc going. @7:11 Just wondering what function is of the two small bronze jets around the edge of the central hole? Cheers,
If we are talking about the same jets, the one towards the top of the screen is the idle air adjustment port and the lower one is where the primer fuel enters your mixture.
Some allow fuel to pass and others air, I believe this one is air but I could be mistaken. I am a novice and my learning is shared to possibly help others with similar issues or learn what not to do.
Dropped it in easily, the PITA was the little retaining clip that follows. I seated it in there using the head of a small round headed bolt and tapped it into place with a small hammer.
So i recently rebuilt my carb and it ran awesome for a few trips now it dies again under load. Wondering if i cleaned it all right. What did u use and where is the actually fuel nozzle that sprays in the engine.
I used a can of carb cleaner and made sure to blow through all orifice holes to make sure I had no obstructions. Make sure to also clean fuel filters and inspect tank for trash/debris if possible.
@@deebomb86 yes sir. It always acted lime it was staved for fuel. And my fuel tank was always blown up or what not. Finally put two and two together. The damn vent in fuel tank was clogged or broke. Bought a new fuel tank and havnt had anymore issues.
Thank you for this video. I have a 8hp but the carb is identical. What is holding the bowl? Is it just that brass screw? I couldn't get my bowl open. Thanks
David Lee On mine it was only the main brass screw in the bottom. The halves were originally slightly stuck together via the gasket. A light tap or two and they separated for me.
My carb is leaking at the choke/primer vent hole when it’s running. Do you think it’s possible to change just that diaphragm? I don’t need a whole carb rebuild since it was just done recently.
Upon taking my carb apart the little ball was missing when I took the 11mm bolt out of the float housing. Spring was there but no check ball. Would this be the cause of my acceleration and low end performance issues? The engine works fine once it reaches higher rpm's but feels like it's misfiring/ stuttering trying to get there.
Was this the issue? Mine is currently misfiring and shaking like crazy until i get it up to higher rpms. While i was cleaning the carb I noticed that the little red ring near the check bulb was coming apart.
SirMarcus, Thank you for the video. Regarding the main New gasket that fits between the Motor and Carb, Did you trim an oblong hole in it that matches the original gasket? Also, where did you order your Gasket kit from? Thanks,
americanworkmule2009 I ordered my kit from Amazon. I searched the part number and keyword Mercury. I marked the new gasket with a pen and cut it out. The sides of the gasket may also need to be trimmed to fit the more rounded opening of your carb. Mine needed this as well upon matching the gaskets up. FIRST, you may want to line the new gasket up to the motor to see if the port is covered or not.
you need to make sure you order the correct carb kit! mercury made several carbs for these over the years, and the kit the poster ordered was clearly the wrong one . no big deal but the correct one would come with the correct carb to intake gasket. for example i have a 1987 25xd. this kit would not work... different fuel pump and primer plus other stuff so i had to order correct kit. the big change came in 1994 when the carb was upgraded to work with the new all-digital ignition system (timing advance was mechanical, but controlled digitally, as was idle)
I'm doing the same rebuild. Did you just put the needle back in or was there a seat to replace? mine doesn't seem to have a seat, and the little rubber seat that came with the kit doesn't fit.
I removed the old needle, it slid out easily, and slid in the new one. I did slide a little metal cap over the float end of the needle and adjusted the float from there. It may show better on my 3rd video of correcting the float.
@@sirmarcusandrew So there *was* a rubber seat that "slid out easily". I hit the carb with compressed air in every orifice and may have blown it out without seeing it. I'm not sure why the little red rubber seat that came with the kit doesn't fit. I'll have to talk to the dealer that sold me the $106.00 kit.
The manual says 1 1/2 turns for idle mixture screw on carburetor for the 20hp’s and 25 hp’s. Different motors/carbs have different jet sizes. www.manualslib.com/manual/1057340/Mercury-Mariner-25-Marathon.html?page=133#manual
I’m as green as it gets with this, so bear with me. At 2:20, you’ve got one gasket on before you put that spring thingamajig on. I re-assembled once and then realized I had all these “extra parts.” My kit has 3 gaskets/seals that fit there. One of the seals looks like the same material used for the diaphragm seal if that helps at all. Hopefully I don’t ruin my motor before someone responds.
![Fixing a 2-STROKE OUTBOARD Motor [Capable Cruising Guides]](/img/n.gif)
I would love to see a video showing how to reinstall the primer assembly. Everything else was easy! Thanks for the videos!!!
My Mercury 9.9 hp outboard, non electric start motor has the exact same carb on it as your 25 hp. I rebuilt it last year and haven't been able to start it. It wouldn't start before because the fuel diaphragm was totally messed up. I searched everywhere for video for 9.9 and nothing, then today, recommendations gives me your video. I gotta check that gasket to see if it too is blocked from fuel delivery. I can rebuild lawn mower motors all dang day and they fire right up. These outboards are a different story for me.
Thank you so much for mentioning that gasket slot. Might’ve just solved my problem. Was still acting like it wasn’t getting gas after a rebuild. I noticed that the new gasket didn’t have the slot but didn’t think twice about it
also be careful with the diameter of the gasket circular opening - on some kits, it is made for 20hp and smaller and not for 25hp which has significantly larger carb outflow opening (as on this video).
I have the exact same carbeurator. I have pulled it apart and cleaned everything and blasted air through every vent I can see. The motor runs for a few seconds if I spray a little gas straight into the carb, but will not run otherwise. The carb bowl is filling up. And when I saw you’re issue with the gasket, I thought I had it pegged. I’m stumped. Been working on this thing for over a week now.
I have some thoughts but I’m not an expert. How new are your spark plugs and did you gap them? When you put the carb back together, where did you set your air/fuel adjustment screw? Do you have the electronic choke? Do you have the “Pull to Prime” option? Is the vent on your fuel tank open and a working primer bulb? Fuel filter been cleaned/changed? And was the motor running at all before taking the carb off?
@@sirmarcusandrew Thanks for the video, very helpful. How do you set the air/fuel adjustment screw? I took the carb apart without paying close attention how far in that screw sits.
@@MarinusVesseur ua-cam.com/video/zm5mB3R8Ucw/v-deo.html See if this helps. I think I am around 3 turns or slightly over if i recall from where I set mine. Watch the last 10 minutes or so of this different video to help as well. ua-cam.com/video/Dnues7Np1Uc/v-deo.html
Idk if you corrected it but you did put the float in opposite of how you removed it in your prior video.
I did. But thank you for noticing/checking. There was a follow up video that addressed my mistakes.
Great job and very helpful. When I put all back together it only starts with starting fluid. But once it starts it runs good. I have 03 25hp electric and pull start. Please help...
Do you have any advise I am going to be doing this and I have never done it. My plan is to take a lot of pictures with notes as I take it apart.
I just bough the carb kit, I was going to rebuild because the primer vent hole has fuel spurting out when I pump primer. Is that new diaphragm going to stop the fuel from spurting out???
Danny B it did on mine. I had a deteriorated primer and the debris blocked the holes and the pressure pushed the fuel out. I cleaned everything out and made sure all ports/holes were free of obstruction.
@@sirmarcusandrew Thank you.
My friend just bought a boat with a 2003 25EL, OT690351 motor. I know I'll be helping him with it when the need arises, so I've been searching for information on it and your videos have been great.
I hadn't realized it was a diaphragm carburetor, so that was good, and highlighting the problem with the gasket was noted.
At 3:29 of your video you "reset" a screw with a lock nut on it, and mention fine tuning it later. What is the function of that screw?
Thanks
It works in combo with a few things. It limits the return of the cold start arm as part of a minimum idle. Set too low (too much return) it will be hard to start and too little return it will rev high like you have the throttle opened too much. I’ll try and get a video made soon to discuss it.
Thanks for the reply. I'll be looking forward to future videos.
Well I was looking for how the gasket set in. I'll continue looking, too fast
Hey mate, thanks for a great walk through. New to the whole outboard scene and am trying to get a 15hp 1993 merc going. @7:11 Just wondering what function is of the two small bronze jets around the edge of the central hole? Cheers,
If we are talking about the same jets, the one towards the top of the screen is the idle air adjustment port and the lower one is where the primer fuel enters your mixture.
Some allow fuel to pass and others air, I believe this one is air but I could be mistaken. I am a novice and my learning is shared to possibly help others with similar issues or learn what not to do.
woulda been great to see how to put the little red seal back in.
Dropped it in easily, the PITA was the little retaining clip that follows. I seated it in there using the head of a small round headed bolt and tapped it into place with a small hammer.
So i recently rebuilt my carb and it ran awesome for a few trips now it dies again under load.
Wondering if i cleaned it all right. What did u use and where is the actually fuel nozzle that sprays in the engine.
I used a can of carb cleaner and made sure to blow through all orifice holes to make sure I had no obstructions. Make sure to also clean fuel filters and inspect tank for trash/debris if possible.
You ever figure out why it dies under load?
@@deebomb86 yes sir. It always acted lime it was staved for fuel. And my fuel tank was always blown up or what not. Finally put two and two together. The damn vent in fuel tank was clogged or broke. Bought a new fuel tank and havnt had anymore issues.
Thanks for the reply man. Much appreciated.
@@XJStryker thanks
Thank you for this video. I have a 8hp but the carb is identical. What is holding the bowl? Is it just that brass screw? I couldn't get my bowl open. Thanks
David Lee On mine it was only the main brass screw in the bottom. The halves were originally slightly stuck together via the gasket. A light tap or two and they separated for me.
My carb is leaking at the choke/primer vent hole when it’s running. Do you think it’s possible to change just that diaphragm? I don’t need a whole carb rebuild since it was just done recently.
I would think so. Possible also check valve O rings where the metal ball and spring is.
Upon taking my carb apart the little ball was missing when I took the 11mm bolt out of the float housing. Spring was there but no check ball. Would this be the cause of my acceleration and low end performance issues? The engine works fine once it reaches higher rpm's but feels like it's misfiring/ stuttering trying to get there.
Was this the issue? Mine is currently misfiring and shaking like crazy until i get it up to higher rpms. While i was cleaning the carb I noticed that the little red ring near the check bulb was coming apart.
@@coryb2726 yes I replaced the missing check ball with one from a grease nipple and it works like a champ
SirMarcus, Thank you for the video.
Regarding the main New gasket that fits between the Motor and Carb, Did you trim an oblong hole in it that matches the original gasket?
Also, where did you order your Gasket kit from?
Thanks,
americanworkmule2009 I ordered my kit from Amazon. I searched the part number and keyword Mercury. I marked the new gasket with a pen and cut it out. The sides of the gasket may also need to be trimmed to fit the more rounded opening of your carb. Mine needed this as well upon matching the gaskets up. FIRST, you may want to line the new gasket up to the motor to see if the port is covered or not.
Thanks,
Measure Twice, Cut once, ...even Factory replacements. Ha Ha
you need to make sure you order the correct carb kit! mercury made several carbs for these over the years, and the kit the poster ordered was clearly the wrong one . no big deal but the correct one would come with the correct carb to intake gasket. for example i have a 1987 25xd. this kit would not work... different fuel pump and primer plus other stuff so i had to order correct kit. the big change came in 1994 when the carb was upgraded to work with the new all-digital ignition system (timing advance was mechanical, but controlled digitally, as was idle)
I'm doing the same rebuild. Did you just put the needle back in or was there a seat to replace? mine doesn't seem to have a seat, and the little rubber seat that came with the kit doesn't fit.
I removed the old needle, it slid out easily, and slid in the new one. I did slide a little metal cap over the float end of the needle and adjusted the float from there. It may show better on my 3rd video of correcting the float.
@@sirmarcusandrew So there *was* a rubber seat that "slid out easily". I hit the carb with compressed air in every orifice and may have blown it out without seeing it. I'm not sure why the little red rubber seat that came with the kit doesn't fit. I'll have to talk to the dealer that sold me the $106.00 kit.
How did you manage to get spring clip back in check ball hole?
Chris Major I used the old air mixture screw. It fit through the whole but was wide enough on mine to catch the spring and push back into place.
I just used an Allen wrench to push mine in and it work perfect.
what is the Number of your mainjet ??
So make sure the gasket has the hole and not the slot?
Mine needed the slot. The new gasket only had the hole and needed a slot made into it.
@@sirmarcusandrew so did mine $85 for an OME kit and had to use the original intake gasket
How many times do you turn your jet out
The manual says 1 1/2 turns for idle mixture screw on carburetor for the 20hp’s and 25 hp’s. Different motors/carbs have different jet sizes.
www.manualslib.com/manual/1057340/Mercury-Mariner-25-Marathon.html?page=133#manual
@@sirmarcusandrew thanks for the manual
Where did you find this rebuild kit.
I ordered it on amazon. MERCURY REPAIR KIT-CARB www.amazon.com/dp/B004QJQHYE/ref=cm_sw_r_cp_api_i_DJPUCbVYZGF1G
please get a better sound system microphone, thanks
I’m as green as it gets with this, so bear with me.
At 2:20, you’ve got one gasket on before you put that spring thingamajig on. I re-assembled once and then realized I had all these “extra parts.” My kit has 3 gaskets/seals that fit there. One of the seals looks like the same material used for the diaphragm seal if that helps at all. Hopefully I don’t ruin my motor before someone responds.
www.amazon.com/Carburetor-Kit-Mercury-6-25hp-2cyl/dp/B01M18LAL7
Aforementioned kit
good video except this.
That's not idle adjustment. That fuel mixture. You should remove this video
You sped it up during the most important parts. Ugh