Kohler ECH749 Over Feulling

[Skywatcher]

Greetings All

A customer brought in a grain auger with a Kohler ECH749-3062 S/N 4513500871 EFI engine that had no power and was blowing black smoke. The anti-icing tube had never been removed since the unit was new in 2015. The exhaust deflector tube was in the sox-o'clock position, so the engine was breathing in its own exhaust and the air filter was black. The rear heat shield had come loose on the muffler and one of the mounting lugs had broken out allowing hot exhaust to blow onto the electronics on the side of the engine.

I've replaced the muffler assembly and air filter, repaired the heat shield and installed a new exhaust deflector in about the 4-o'clock position. The oxygen sensor was caked thick with carbon which came off with compressed air. The sensor also checks out according to the resistance specs and the anti-icing tube has been disconnected. The engine appeared to be running fine when it left my shop, so figured it was fixed. Received a phone call from the customer saying the engine now has a lot more power, but the snow is turning black under the exhaust deflector pipe. This tells me the engine is still over-fueling. Any suggestions? Thanks,

Sky

[KE4AVB]

I don't have much experience EFI systems yet but it may still be that O2 sensor or leaky injector.

Are you getting any error codes?

[Luffydog]

O2 sensor in the exhaust more than likely is bad or had low voltage. Replace that might have to do a relearn on the computer at the port. But I would say just replacing that part will fix the issue and the computer will store it in the historic

[Skywatcher]

Greetings Once Again

Figured I'd give an update on this unit. The customer borrowed an O2 sensor from another EFI Kohler and the engine runs a lot better. Have ordered and received an new O2 sensor, customer will pick up and install on Thursday. Have also been in contact with another small engine shop that has the capability for hooking up a laptop to the engine to run a full diagnostic.

Customer indicates he will finish loading last year's grain, then get the auger over to the other shop for the computer hookup before spring seeding. I'll try and remember to give a final update once the unit has had a chat with a laptop. All the best.

Sky

[bluemower]

If the o2 sensor or cable has failed, the engine will assume a default setting. This will allow the engine to run, but is not close to "spot on". Valve clearance that is set too tight will cause richer mixture.

does this have a pulse pump that delivers fuel to the efi pump? if so, check the crankcase oil for fuel.