Kohler 26 EFI ?

[bwa]

I have an exmark with the kohler 26 efi and i was wondering if anyone is familiar with these engines. Every morning or when the motor is not warm it idles really rough and has no power, it almost dies but never does it runs normal after it has warmed up. does anyone have any ideas on what the problem may be?

[TRANSMAN]

GUESS.

I will hazard a guess as nobody else has yet. I have no experience with this particular motor so it is only an educated guess. Being 26 hp im guessing its a twin. I assume it has one fuel injector that injects fuel into some sort of throttle body that feeds two seperate plastic manifolds that feed each cylinder and one is leaking air because there is a crack or gasket leak.That would lead to one cylinder running lean which will start produceing power as it eventually warms up because hot engines tolerate leaner fuel air mixtures..Regardless you dont want one cylinder dragging the other along because it will lead to accelerated wear like a burned exhaust valve. The other possibility is if it has a solid lifter valvetrain possibly the valvetrain clearance is tight and as it warms up the valveseats and valvehead heat up and expand enough so the cylinder begins produceing compression/power. In that case you just have to adjust the valve clearance.Regardless you dont want one cylinder dragging the other along untill its warmed up so it should not be ignored but immediately fixed.GOOD LUCK,SINCERELY

[bwa]

Thanks Transman i took it to the shop today and they thought it was the muffler flanges or the exhaust gaskets, they put new exhaust gaskets on it and it was running fine when i left the shop but when i got home it was doing the same problem i called them back and they said it was probably the muffler flanges. They said i would probably have to buy a new muffler which is 200 i guess it is so high because it has a whole to mount the oxygen sensor in it . They seem to believe it is sucking in air and when it warms up it seals off. What do you think about what they told me today? Could i double up on the exhaust gaskets maybe? Thanks again Transman

[1Chavez]

Maybe it's the muffler bearings or you're low on headlight fluid.

I haven't come across this particular engine yet, but a leaky exhaust will only effect performance if in such an enclosed area that the exhaust gasses are entering back into the intake. As for double gaskets, why not take off the muffler and have the flange machined (at a machine shop) flat, double gaskets are highly not recomended. It sounds like your shop might be right, but I would agree with Transman that your leak is happening on the intake side instead of the exhaust. I am very interested to hear the results because I might have the same engine in my new Walker for the spring.
-Rich

[TRANSMAN]

Hmmmmm

This is very tricky without seeing. If the exhaust is leaking anywhere i would think YOU could and should hear it when cold.Do you hear any leaks whatsoever?. If a flange was warped enough to cause this serious leaking/ rough running i would expect that the gaskets they replaced would have been completely blown out.WERE THEY? They probably conveniently wont remember and dont know because they threw them away.If they are blameing the oxygen sensor thinking its getting a false lean condition reading then i would suspect the misinformed sensor would send a signal to the computer increasing the fuel injected to compensate and you would have black smoke billowing out the exhaust like a carburetored engine thats running with the choke closed.IS IT RUNNING RICH AND BILLOWING BLACK SMOKE??. Am i even correct thinking it has one injector feeding both cylinders or is it some ultra modern design that has port injection and possibly one injector for each cylinder? I appologize for all the questions but without knowing these specifics i can only guess at guessing. Being im asking all these questions does it have plastic manifolds leading to the intake ports? Small engines are useing these on other designes and i have seen a few cracked or just loose. The more specific the better i can narrow the likely possibilities. I know you said it runs rough in the morning cold but does it start right up or do you have to crank it considerably /excessively to get started? I would like to be able to help because it sounds like there starting on that ( WELL LETS CHANGE PARTS AND JUST KEEP CHANGEING THEM ONE BY ONE AND CHARGE THIS GUY TILL WE FIX IT) and that is a waste of your hard earned money and there lack of troubleshooting abilities.If its under warrenty and not costing you let them change away at there expence.SINCERELY