Misfiring (spitting gas out carb)

[Fortney]

I cleaned the carb out on my 1961 40 HP Evinrude. An old cork gasket had been disintegrating and bits and pieces collected into the fuel system and carb. Initially I cleaned out the bowl and metering valve/needle, slapped it on and it purred - for a few minutes, then it started misfiring and spitting out gas from the carb. Figuring it got more debri, I pulled it off and cleaned it again. Same thing, it purred for about 5 minutes then started missing and spitting. Third time, I did a more thorough breakdown and cleaning, it purred for longer this time but sure enough, it begun missing and spitting again. Before I tear the carb down yet again and blow all of the lines, I wanted to pick some brains and see if I should be looking at something else first. The plugs have been tested and are gapped and clean (no water/black, corrosion, etc) - NOTE: JUST PULLED THE PLUGS AGAIN AND THEY WERE BLACK. I couldn't imagine that this is a timing issue seeing how the problem is corrected only after cleaning the carb. I've also played wit hthe rich and lean lever (only way to adjust the air/fuel mixture on this engine) and there was no improvement. One more thing, I havent worked on an older outboard like this before, and I'm pretty sure it's normal but I wanted to check to be safe - the exhaust spits out water, I've assumed this was part of the cooling.

 

[nwcove]

Re: Misfiring (spitting gas out carb)

did you re-kit the carb or just blow it out?

 

[pn]

Re: Misfiring (spitting gas out carb)

when you blow out the carbs do you find any debris? old fuel lines can dissintegrate from the inside. make sure a fuel filter is installed and that your gas tank is venting.

 

[Fortney]

Re: Misfiring (spitting gas out carb)

Yes, the first and second time I did. However, the third time I didn't. I tore down the the carb completely the third time, the first 2 times was mostly bowl service and blow + spray. I did however notice that this issue seems to only take place when the motor heats up, when I let it cool down, I fire it up and for the first few minutes it runs like a champ and then and begins to mis, stall and spit. and it continues to do so until it cools down again. Any thoughts?

 

[bplayer405]

Re: Misfiring (spitting gas out carb)

Spitting gas out of the carb can mean a lean mixture. If you haven't done it yet, take the mixture screw you mentioned completely out of the carburetor and check the passageway for debris. Remove the carb and spray carb cleaner into the small hole on the intake side of the closed throttle plate to clear the idle circuit.

 

[Fortney]

Re: Misfiring (spitting gas out carb)

bplayer you replied around the same time I posted my response to nwcove and pn - yes I did clean it out (I serviced pretty much the entire carb. Will do it again if I have to, but, this could be caused by something else, please see my post just prior to yours for more details.

 

[nwcove]

Re: Misfiring (spitting gas out carb)

does that motor have the inspection plate on the flywheel? .....if so have a look at the coils, they may be original and if so, they are surely nfg.

 

[bplayer405]

Re: Misfiring (spitting gas out carb)

Ok, does it act like its dropping a cylinder when it acts up?

 

[Fortney]

Re: Misfiring (spitting gas out carb)

bplayer - I'm yes, when it's really bad, it's as if one cylinder is not going through the motions and the other is keeping it alive

 

[Fortney]

Re: Misfiring (spitting gas out carb)

nwcove, hmm, not sure, but I was thinking my next step might need to be to replace the coil and wires.

 

[bplayer405]

Re: Misfiring (spitting gas out carb)

If there's only 1 carb then I would start looking at the coils and plugs. An inductive spark tester will tell you if you're losing spark on a cylinder. I have a mariner with two carbs and it acted like yours is. It ended up needing a float adjustment cause one needle wasn't seating.

 

[nwcove]

Re: Misfiring (spitting gas out carb)

Evinrude Magneto Parts for 1961 40hp 35524 Outboard Motor

part # 7 . pull the wires off the plugs to prevent accidental starting, remove that cover, rotate the flywheel cw until you can have good look at each coil, you should be able to tell if they are original....you can also clean the points through that hole.

 

[Fortney]

Re: Misfiring (spitting gas out carb)

Thank you guys, this is all helpful stuff.

 

[ilovevintage81]

Re: Misfiring (spitting gas out carb)

Try using new gas. Water could be in gas or probly coil if it does that after getting warm

 

[ilovevintage81]

Re: Misfiring (spitting gas out carb)

I have 71 evinrude 40hp it backfires just like that but if i set idle a little higher it wont backfire

 

[Fortney]

Re: Misfiring (spitting gas out carb)

ilovevintage: That's a good idea, I will try replacing the gas. Also, it's interesting that you say that regarding the idle, I had noticed earlier that the missing seemed to change when I adjusted the idle, unfortunately, I could not find a sweet spot.

 

[ilovevintage81]

Re: Misfiring (spitting gas out carb)

Mine did that then after reving up for awhile then it quit next day would idle real low and not jerk at all now its doing it again even when i rev it in high rpms well my gas is like 5 to 10 years old and real dark plus gas line is new but srill not sealing good i think im going to put real clamps on line thats what i had to do on another boat but it could be gas i thought it was just carb cause run fine after cleaning with my secret trans carb cleaner but my gas is black thats probly why so much oil in my tub too i was just to cheap to buy new didnt want to waste the gas maybe ill use it to burn all this scrap wood i have out back

 

[ilovevintage81]

Re: Misfiring (spitting gas out carb)

Mine wasnt the gas it was the screws needed adjusted try screwing all the way in then out about two turns then adjust from there but count turns so you know where it was before mine quit backfiring but cant get to idle really low

 

[kodibass]

Re: Misfiring (spitting gas out carb)

well if you pull the carb to clean it again take a peek in the intake, Iv had one or 2 over the years that did a little back spitten from reed issues.