Kohler 26EFI Dropping RPMS? Any help?

[MOW ED]

This is a truly perplexing situation for me. My 26EFI which has been realy reliable for 1500+hours has been giving me fits lately. Actually it started last year about this time. The motor would be running great on one job and then the next job I would fuel up and shortly after the thing would drop rpms and then increase. It would smell like the motor was loading up (fuel exhaust smell rich). The R's would go up and down but the engine would never quit, it would do this with or without the blades engaged. BTW this is on a Walker GHS with the 42 deck. The funny thing is that I may have a heck of a time on one property with it doing this and then the next stop it will run with absolutely no problem. It is truly an inconsistant problem that has me scratching my head.
I thought it may have been a dirty fuel filter and replaced it. I took the fuel pump out of the tank and inspected it and cleaned the tank and screen. I checked the best that I could for wiring issues and still think it may be wiring but I am really stumped.
When it is doing this I sometimes play with the linkage to increase the r's a few times and it seems to make it go away. Almost like if the choke is stuck on an old vehicle but this is an efi.
Can anyone throw some ideas my way, I will listen to all.

I know that I can take it to my dealer but I am so swamped that this ain;t happening until it isn't running at all or I get a rain day. Thanks.

[TLS]

Gas cap vents clogged?

[JJ Lawn]

When you changed the filter on the fuel pump, did you look up into the intake of the pump itself? When I did mine I noticed that the old filter had started to deteriorate and was plugging up the pump.

This was the problem with mine when it ran as you described.

Also you migjht want to check for small pin hole's in the two rubber lines connected to the pump. This could also cause what you describe.

[Likestomow]

Did you try cleaning out the carb?<G>

My guess, and it's only a guess, is there is some malfunction with the computer or a sensor. I'd call your Kohler distributor and start asking some questions.

Please let us know what you discover the problem to be... I have a 28EFI.

[lucforce]

Clean your grounds for the efi harness.

Check the fuel pressure.

[Partsangel]

Liketomow
(I'd call your Kohler distributor and start asking some questions)
Lucforce
(Clean your grounds for the efi harness)

Kohler EFI units have a code to follow. turn your keyswicth on then off three times and a series of codes will blink on your control box. ask what the series of blinks means at your local Kohler Dealer. Im thinking that the EFI ground could be your problem like Lucforce has mentioned.


Mike AKA Partsangel

[Birdman]

It's the air filter.

[fixer67]

It's the air filter.

It may be the air filter sure enough. Had one in the shop that some one had put the air filter in backwards and it was cutting off the air flow. Sounds like a dumb thing to do but someone did it. Post your engine trouble codes. By the way do not go messing with any wiring or such unless you know what you are doing. These ECUs cost $500 to replace if you fry it. Just replaced two this month fryed from jump starting.

[MOW ED]

Thanks for all the input. Some really good ideas to try. I did check the fuel cap and it vents well. I cleaned the air filter many times. I only changed the fuel filter outside the pump. I will definately check the pump filter and the pin hole problem. That sounds good. No carb on this guy.
Can someone tell me or show me where to check and possibly clean the grounds? It seems like an easy thing to do but I want to do it right. Thanks again. I'm going out to use it now so I will let you know later. Stay safe.

[Brianslawn]

its bushs fault.

switch out the o2 sensor. reset puter, run it.

what codes you got now? whats your fuel pressure?

[lucforce]

mow ed,

99% of all driveability problems are not bad computer or sensor. They are usually due to a lack of routine maintenence, a faulty electrical connection, vacuum leaks, or some failed electrical component(not including computer or sensors).

Many "techs" start by replacing parts for, whatever, reasons. Then they have to fix the problem, still. The simple things are what make or break any computerized system.

I can not remember offhand where, exactly, the grounds are on a wlker fuelly. You should be able to look around and find them, though. They easily work loose or get corroded. On a fuel injected lawn mower, this is something that should be checked on regularly. Also check the battery connections. They should be CLEAN and TIGHT.

With a quality voltmeter, not the guage on the machine, check the battery voltage. Start the machine and check the charging voltage at the battery. Do this with the engine at full throttle and at idle..

Next, check the fuel pressure. You will also want to check the fuel pressure while the thing is running bad. If the pressure is low you either have a weak pump or the fuel pump relay is causing problems.