update-used today after big storm & still revs up & down & stalls or wants to stall with engine hot(temp guage in normal zone). if I choke it when it is almost stalling it picks back up then runs normal. I can give it more throttle while its trying to stall & then runs normal. cleaned gas tank put in new screen & cleaned sediment bowl & new high test gas, but same results.
- Thread starter Rkh
- Start date
Allan in NE
Well-known Member
Carb icing?
Allan
Allan
Russ from MN
Well-known Member
- Location
- Bemidji MN
High test gas is for high compression engines. I agree with carburetor icing.
MarkB_MI
Well-known Member
- Location
- Motown USA
Not sure what kind of device you're talking about. Generator? Tractor? Chainsaw? Lawnmower? Motorscooter?
Surging on any engine with a governor is often due to a blocked carburetor idle circuit. Under low load, the throttle will close to the point where the idle circuit starts to take over. If the idle circuit is blocked, the RPMs will droop, causing the governor to open the throttle, kicking in the high-speed circuit. RPMs raise, throttle closes and the cycle repeats.
Cleaning out all the carb passages and jets with a fine wire will usually fix the problem. This is tough to do on newer carbs, so it may be necessary to replace the carb. Closing the fuel and running the carb dry before you store the engine will prevent this in the future.
Surging on any engine with a governor is often due to a blocked carburetor idle circuit. Under low load, the throttle will close to the point where the idle circuit starts to take over. If the idle circuit is blocked, the RPMs will droop, causing the governor to open the throttle, kicking in the high-speed circuit. RPMs raise, throttle closes and the cycle repeats.
Cleaning out all the carb passages and jets with a fine wire will usually fix the problem. This is tough to do on newer carbs, so it may be necessary to replace the carb. Closing the fuel and running the carb dry before you store the engine will prevent this in the future.
jimg.allentown
Well-known Member
Lean mixture. Choking proves it. Could be partially plugged jet, low fuel level in the bowl, or adjustment if it is adjustable.
todd hamilton
Member
or manifold icing - what kind of tractor is it?
DENNIS MIN
Member
Jimg.,
I'll second that lean notion. Plugged jet, obstruction, something.
D.
I'll second that lean notion. Plugged jet, obstruction, something.
D.
old
Well-known Member
- Location
- Camdenton Missouri
Helps us help you if you tell us what it is that runs poorly.
If it is a tractor pull the carb drain plug and let the gas run a few minutes. Catch it to look for water/dirt in it. Good chance you have a little dirt/rust in the main jet of the carb and by choking it your pulling a little of it out of the main for a few minutes. Some times you can pull the air cleaner tube off and put you hand over the carb with it running and that some times is enough to pull the junk out of that jet
If it is a tractor pull the carb drain plug and let the gas run a few minutes. Catch it to look for water/dirt in it. Good chance you have a little dirt/rust in the main jet of the carb and by choking it your pulling a little of it out of the main for a few minutes. Some times you can pull the air cleaner tube off and put you hand over the carb with it running and that some times is enough to pull the junk out of that jet
rpm hunting that stalls, and can be helped with a bit of choke is usually a fuel starvation situation.. engine stalls.. gov opens throttle up.. more fuel i sucked in.. engine overrevs.. gov closes throttle. all starts over. applying a lil choke usually reduces the hunt or stops it at a certain choke / throttle setting / set laod... assuming fuel supply can keep up.
check fuel delivery system.
check fuel delivery system.
It does sound like a lean condition if opening the choke helps. Could the idle circuit in the carb be partially plugged or adjusted too lean? The engine surges because the governor has to keep re-opening the throttle until the main jet takes effect and the engine only runs on the main jet instead of on the idle circuit.
I would try opening the idle adjustment to test this idea.
I would try opening the idle adjustment to test this idea.
Oliver662011
Member
Good advice on dirty carb might be the issue or icing due to this weather. But I would recommend against using wire to clean a carb it could result in gouging of the passages especially in aluminum carb bodys. I would use carb cleaner, and/or parts washer and use compressed air.
Mike
PS: Don't look into the passage when blowing it out, learned from experience.
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