Kohler ECV749 mower engine issues on an eXmark X-Series 60" zero turn

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May 29, 2019
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84
Location
Michigan
Looking for some help on a friends ~2012 eXmark X-series with a Kohler ECV749 EFI engine and the 60" deck. Running on one cylinder at idle and then really rough at full throttle with RPM's surging with no load and smells like it's running VERY rich.

Put in new air filter as the one that was in it was quite dirty and packed with grass and also replaced the spark plugs which made no difference. Though the rear facing plug was very carboned up almost to the point of closing up the gap between the electrodes and the front spark plug looked completely normal/fine. Checked both ignition coils, those are both good. Did a compression test on both cylinders, which is a little misleading and hard to go by with the automatic compression release. He did say this engine has been burning some oil and insisted on using Castrol GTX High Mileage 10W-40 with like 50/50 mix of that and Lucas Oil stabilizer when I did the oil change. I actually used maybe only 1/2 a quart of the Lucas because it's so thick, I think that it might be doing more harm to the engine than good using that much in comparison to the oil. MY opinion is that is the oil alone can't do the job then what benefit is an oil stabilizer product like Lucas? Anyways...

The mower has approximately 2200 hours on it and has done a variety of commercial lawn care along with leaf cleanup with the rear mounted bagger attachment that Dave has which he uses for spring cleanup and fall leaf cleanup. He took it to a local reputable lawn equipment dealer last fall to try and get things sorted out but they were not able to determine the cause of the problem.

I suspected one of the fuel injectors would be hung up (because of the heavily carboned plug on the rear facing cylinder) so I pulled those out last night with the fuel line still connected and the rear injector is squirting A LOT of fuel compared to the front one. So I thought process of elimination... I swapped the injectors from front to back and repeated the same test and the rear injector is still spitting way more fuel than the front one. At this point this sounds like some sort of electrical issue which exceeds my level of expertise with these newer EFI lawn mower engines.

I disconnected the battery before I left for work this morning hoping that would reset the ECU or something and then I'll tinker with it some more when I get home today.

The ECU mounted on the engine cover says DELPHI on it so does anyone know if there is a way to reset the ECU on this engine? And if there is a teach process to reprogram it?

What would cause the engine control system to command way more fuel for the rear cylinder only and not both?

Any additional thoughts or advice would be appreciated!

Regards!
 

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Joined
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Connecticut
If the dealer couldn't figure it out, time to bring it to another dealer/shop. The problem I've seen with many of the commercial mower dealers around here is they see a commercial landscaping company with a broken mower and they want to put more effort into selling them a new mower than diagnosing the current high hour machine.

While these engines do have a compression release, you can still test compression. It just means that the actual compression numbers will be slightly higher. What you are looking for is consistency. If one is much lower than the other then you have an issue. I just worked on a similar Kohler that ran poorly, it had leaves and mouse nest material built up around the cooling fins, and it blew a head gasket.

I would check the voltage with a meter at the injector harness connectors to make sure you don't have a short somewhere.

I definitely would keep Lucas out of a small engine. Just run a good 15w40 or if it burns a ton of oil a 20w50.
 

1911CHAMPION

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Joined
May 29, 2019
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Location
Michigan
I definitely would keep Lucas out of a small engine. Just run a good 15w40 or if it burns a ton of oil a 20w50.

He gave me a whole gallon of the Lucas and said he runs it 50/50 with the Castrol 10W-40. I'm thinking that is a lot of unnecessary strain on the oil pump...

I "poured" a quart from the jug of lucas into an empty quart oil bottle that I had and added half of that to the eXmark and half to the Scag I also did an oil change on. That old oil drained out like gear lube even when the engine was hot.... 🤦‍♂️
 

1911CHAMPION

Thread starter
Joined
May 29, 2019
Messages
84
Location
Michigan
Update on the Kohler EFI v twin

The throttle position sensor was bad. I put a new one in and did the ECU reset and the tps learn procedure and now it runs awesome!

Definitely rekindled some new life into this “high mileage” engine.

Thanks for the responses!
 
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