Kohler efi 27hp fuel starvation, wierd

[TimberMcPherson]

engine starts starving on chipper after a few minutes running WOT. bit of black smoke when it happens. shut it down and engine will restart fine, run then start starving again.

I have installed new fuel filter, the fuel level is above the filters placement. tank is half full, tried venting tank while its starving and it made no difference

checked the mechanical pump on engine (its pumping about a half cup of fuel a minute) while idling. took the pump a part and it looked fine, no holes in the rubber that I could find.

if I take off line going into mechanical fuel pump and direct it into a fuel container on ground, it gravity flows fine.

in operation its starving if the fuel filter is horizontal or with the inlet side down. if I turn the inlet side up it seems to stop starving and runs fine. Im treating this as a symptom of trouble further up the fuel system not the problem!

Exhaust manifolds on both sides have hairline cracks, have had new one on order for months. Muffler has exhaust censor for efi in it.

What do you think? could there be a partial blockage in high pressure pump? could cracks in exhaust effect operation of high pressure pump? I dont have a fuel pressure gauge to test pump in operation. According to kohler the high pressure pump has no suction capability. guess an air leak is possible somewhere I have yet to find.

Oh and if you have a chipper or stumper with the kohler engine and it seems to start getting hard to start randomly, cranks but doesnt go but then runs fine, take the ignition system apart behind the key, you may find a heap of sawdust and chip in there thats stopping the contacts working

 

[ballisticdoughnut]

May wanna check to see if it's got any fault codes stored. I just repaired a stump grinder with a very similar problem, turned out to be a faulty O2 sensor. That exhaust manifold needs to be replaced if it's cracked. The O2 sensor may be detecting excess oxygen and trying to compensate. Pull codes and go from there.

 

[Del_]

Does it have a low oil pressure detection system?

 

[les-or-more]

May wanna check to see if it's got any fault codes stored. I just repaired a stump grinder with a very similar problem, turned out to be a faulty O2 sensor. That exhaust manifold needs to be replaced if it's cracked. The O2 sensor may be detecting excess oxygen and trying to compensate. Pull codes and go from there.

Had a welder acting like it was running out of fuel, O2 sensor fixed it.

 

[TimberMcPherson]

May wanna check to see if it's got any fault codes stored. I just repaired a stump grinder with a very similar problem, turned out to be a faulty O2 sensor. That exhaust manifold needs to be replaced if it's cracked. The O2 sensor may be detecting excess oxygen and trying to compensate. Pull codes and go from there.

yes, I have had it on order for a while. Will run the thing monday and try the codes then. Its sunday and I try not to disturb the neighbourhood by running gear on weekends

 

[TimberMcPherson]

Does it have a low oil pressure detection system?

Does have an oil sentry, of course, I didnt think of that. did an oil change a month back, will double check.

 

[Del_]

Do you have an inline spark detector?

It would be interesting to know if it still had spark as it was dying.

 

[TimberMcPherson]

Do you have an inline spark detector?

It would be interesting to know if it still had spark as it was dying.

That wouldnt explain why the angle of the fuel filter effects the starvation issue, will look into it

 

[Oletrapper]

Just a couple of thoughts. You said it blows some black smoke when it acts up. To me that would indicate excess fuel. A bad low oil sensor will simply shut the engine down. No spark.
I am leaning towards the O2 sensor and cracked exhaust manifolds as others have said. The codes should tell you. If they say bad O2 sensor it may still be good as your manifolds are cracked. Keep us posted on what you find.
OT

 

[SweetMK]

Electronics on engines "do not play fair",, you never can figure out what they are thinking,,
so, I would recommend that you check the air filter,, as well as the path air takes to get to the filter.

I just worked on a chain saw that began running much better because I cleaned a screen that was in place ahead of the air filter.
The screen did not look that bad,, go figure,,,,,

Also, does the engine have the sensor in the incoming air stream? I see one listed as a replacement part for some Kohler engine.
There is a spray that will clean the mass flow air sensor.
I think there is something special about the mass flow air sensor that stops you from cleaning it with brake cleaner.

I just worked on my daughters 2007 Chevrolet pickup with a 4 cylinder engine. It had more fuel injection sensors than you can imagine,, and at 160,000 miles, they ALL needed to be replaced,,,,,,,,,,,,,,,,,

 

[TimberMcPherson]

Man you guys are great, I have been beating my head against a brick wall with this thing, at least you guys are here to say "yeah do that again with one eye closed to see if thats easier." its appreciated.

I thought you got codes from it by turning the ignition on and off 3 times, leaving it on the third time, thats not working with my machine. But I have changed the oxy sensor after it screwed around again today, will test tomorrow

 

[Oletrapper]

engine starts starving on chipper after a few minutes running WOT. bit of black smoke when it happens. shut it down and engine will restart fine, run then start starving again.

I have installed new fuel filter, the fuel level is above the filters placement. tank is half full, tried venting tank while its starving and it made no difference

checked the mechanical pump on engine (its pumping about a half cup of fuel a minute) while idling. took the pump a part and it looked fine, no holes in the rubber that I could find.

if I take off line going into mechanical fuel pump and direct it into a fuel container on ground, it gravity flows fine.

in operation its starving if the fuel filter is horizontal or with the inlet side down. if I turn the inlet side up it seems to stop starving and runs fine. Im treating this as a symptom of trouble further up the fuel system not the problem!

Exhaust manifolds on both sides have hairline cracks, have had new one on order for months. Muffler has exhaust censor for efi in it.

What do you think? could there be a partial blockage in high pressure pump? could cracks in exhaust effect operation of high pressure pump? I dont have a fuel pressure gauge to test pump in operation. According to kohler the high pressure pump has no suction capability. guess an air leak is possible somewhere I have yet to find.

Oh and if you have a chipper or stumper with the kohler engine and it seems to start getting hard to start randomly, cranks but doesnt go but then runs fine, take the ignition system apart behind the key, you may find a heap of sawdust and chip in there thats stopping the contacts working

Can you give us the exact model number on the engine? Command Pro?
ECH749 maybe? Just curious.
I am running 3. 2 on ExMark Lazer Zs and 1 on Woodmizer HDLT 40. All 3 are 27HP. Mine are all carburetor and not EFI however. Older models. Thanks, OT