My Tractor Forum banner

1 - 12 of 12 Posts

·
Lawn Boys Never Die
Joined
·
2,049 Posts
Discussion Starter · #1 ·
My recently aquired and de-crusted 5247 is still surging. I tore the carb apart and gave it a good cleaning to no avail. I checked the float and needle and seat and all seem to be ok and working. If I keep priming it it will smooth out, but it will start surging again and eventually shut off. I am guessing that it is straving for fuel, but I am not sure what to do. I tried adjusting the screw on the carb, but I am not sure what I should be doing as far as turning it in or out. Suggestions??
 

·
Registered
Joined
·
1,372 Posts
Maybe it isn't starving for fuel. It might be overdosing on air. That is to say, you could look for bad seals to rule out a vacuum leak.
 

·
Lawn Boys Never Die
Joined
·
2,049 Posts
Discussion Starter · #3 ·
Maybe it isn't starving for fuel. It might be overdosing on air. That is to say, you could look for bad seals to rule out a vacuum leak.
I replaced the gasket on the carb bowl, but not the gasket that goes between the carb and the engine. I was going to try this next.
 

·
Lawn Boys Never Die
Joined
·
2,049 Posts
Discussion Starter · #5 · (Edited)
When you prime the carb, where does the gas spray out of in the hole in the carb?
Sometimes from the jet and sometimes from the little hole just in front of the jet. Both the upper and lower seals are dry as a bone.
 

·
OMC & Ariens lover!
Joined
·
1,296 Posts
check lower seal,i had to replace the one in mine ,now it runs perfect.
 

·
Registered
Joined
·
2,420 Posts
Sounds like you have a bad carb to flange gasket. My 7268 did same thing. I replaced the gasket and it is a good as new after a good EVEN snugging of the carb bolts. Mine was surging like crazy.
 

·
Lawn Boys Never Die
Joined
·
2,049 Posts
Discussion Starter · #8 ·
seals are good, in fact the underside of this mower is so clean. It had a very light coat of grass on it. I took a sanding block over it and it looks like a brand new deck. GTP, I was thinking some type of air leak, that gasket was my next thing to replace, thanks for the advice.
 

·
Deceased, April 2015
Joined
·
190 Posts
If constant priming is the only way to get it to run well, you almost certainly have an air leak. The plastic carbs are notorious for warping at the base flange. As GTP suggested, replace the gasket. I've also coated the gasket with a thin coat of gasket sealer such as the non-hardening Permatex and used large flat washers under the lock washers on the carb screws. Tighten them incrementally and snug. Your air leak should go away.

Good luck.

Charlie
 

·
Lawn Boys Never Die
Joined
·
2,049 Posts
Discussion Starter · #10 ·
Ok, a little update. I put new gaskets on the carb, Still surging. I swapped out the old carb for another newer f engine carb, still surging!!! It will even out if a prime it, but then goes back to surging eventually. Lower seal is dry, I pulled the muffler off, ports are good
I can only think of two other things the upper seal and the coil. Not sure how to tell if the upper seal is bad.
Could the coil be checking out?? As in spark is dying out as its running?? I have also noticed it needs to be primed to start even after it has been running.
I am leaning towards the upper seal.
 

·
Registered
Joined
·
247 Posts
My experience with small engine coils is that when they are fatiguing the engine will start and run when cold, but stall when hot, then start again when cold.

My C21CPN had a surging problem that was fixed when I replaced the governor spring which had been bent out of shape by a PO.
 

·
Registered
Joined
·
2,420 Posts
Ok, a little update. I put new gaskets on the carb, Still surging. I swapped out the old carb for another newer f engine carb, still surging!!! It will even out if a prime it, but then goes back to surging eventually. Lower seal is dry, I pulled the muffler off, ports are good
I can only think of two other things the upper seal and the coil. Not sure how to tell if the upper seal is bad.
Could the coil be checking out?? As in spark is dying out as its running?? I have also noticed it needs to be primed to start even after it has been running.
I am leaning towards the upper seal.
Shoot some carb cleaner around the case seam too..you may have a slight case leak causing it to go lean/rich-it you spray the cleaner and nothing happens your case is tight-if it accelrates or stumbles you have aleak. Also could be the upper seal, i've seen a few get really dry and just not seal well.
 
1 - 12 of 12 Posts
Top