View Full Version : Code on Fuel-Injected Engines (EFI Kohler on Exmark Lazer)

09-29-2009, 07:28 PM
My EFI kohler has been to the shop many times , and they cant find the problem.

When it gets hot.. after 3-4 hrs of use, it will gasp and snap and sputter like its runnig out of gas, or like its timing is off.

I can bleed the fuel line , and it helps a bit.(always seems to have air in line when hot.

I can park it under a tree to cool it off , but it sounds horribly unprofessional , and I am wondering if any other EFI owners have had a problem.

The blinking red light code gives this... 3 blinks pause, 4 blinks , in this order

i need a new cpu module?

09-29-2009, 07:56 PM
Has the dealer used a computer to diagnose the problem?

How old is the unit?


09-29-2009, 08:00 PM
yea, but the codes throw him off.

its about 4yrs old

09-29-2009, 08:03 PM
I have had a problem with mine for about 4 years come and go no rhyme or reason. I believe a code 34 is the oxygen sensor. I have replaced several things, oil sending unit twice oxygen sensor twice, fuel pump, rocker arm came off, and replaced the lifters and its finally fixed.

09-29-2009, 08:08 PM
would a bad fuel pump make sense only when hot??
I have been thinking of replacing that , since it does grunt and groan , and sometimes seems to have air in it , and not pushing gas.

09-30-2009, 04:38 PM
"oil sending Unit" ... is that something easy to replace??? I have felt for some time , like it must be a cooling issue, with not sending enough oil through the machine...

any one know??

09-30-2009, 09:09 PM
I can bleed the fuel line , and it helps a bit.(always seems to have air in line when hot.

I may be way off on this, and I'll explain. Back in the day I had a 64 Pontiac GP with the big 455 engine. It would run great in the winter, but come the summer, you could not take it for long drives. Problem was the the fuel line ran near the headers, causing vapor lock, fuel bubbling in the fuel line. At the time, I wasn't going to put the time or effort in to rerouting the fuel line, the beast was a beater :laugh: Now my cheap fix at the time was to wrap the fuel line ( it was metal ) in aluminum foil, like a heat shield.

My suggestion would be that the next time this happens, trace the fuel line back and see if there is any place where it is really hot. If you find a hot spot, either move the fuel line or make up a heat shield and see if this works

Just a thought.. Good Luck :drinkup:

09-30-2009, 09:15 PM
Thanks, I do appreciate it.

I dont think there is uch to be able to change since some of the gas lines run through metal tubing tight close to the carb intakes.
It didnt use to do it.
another theory was the ethanol in the gas.

i looked up the code 31 and 34 are both from running lean , which could be vapor lock , but it alos mentioned the fuel pump , fuel condensor and oxygen sensor.

I may just order those all and install it myself.

i wish they could give me real gas again without the ethonal ... messing up my small equipment too.
i use sentry plus gas additive for that , helps some.

09-30-2009, 09:31 PM
If it's running that lean, you better fix it quick.Both the codes are related to the o2 sensor. That doesn't mean it's bad. Could have lost ground, exhaust leak or bad connection or sensor. Check the fuel pressure first at the fuel rail. You need 40psi. How old is the high pressure filter? Code 34 could be a bunch of things. Check the simple first. You didn't add an other fuel filter into the system?

09-30-2009, 09:36 PM
No I havnt added a filter.

I bought it used about 2000 hours ago , and filter hasnt been changed. But i dont think that would make it skip and pop when hot only. needs to be changed anyway I guess.

How do I check the fuel pressure?? i need a special guage? any ideas where to order one?


09-30-2009, 11:07 PM
Codes 31 & 34 are both oxygen sensor codes. That doesn't mean the oxygen sensor is bad. It could be but it could simply mean that the oxygen sensor is sensing a lean or rich mixture. And yes you should check fuel pressure. Any standard automotive fuel pressure gauge will work. You should have between 36 and 42 psi of fuel pressure. You need to check the fuel pressure when the engine is acting up. If it's running good the fuel pressure will be good.

Two Seasons
09-30-2009, 11:13 PM
If these EFI engines are set up like car/truck engines, then if you're coding "lean" it isn't the oxygen sensor. Here's why...the oxygen sensor, once defective, causes the CPU to go to a default "full rich" mode.

I'm thinking it's the fuel pump too.

10-01-2009, 12:47 AM
The first thing you need to do is perform a full service on the unit. This engine will run 4000 hours or more if taken care of.

My shop was the beta site for the Bosch software for the state of Florida. If you will send me your serial number and model number I can get you some advice.


10-01-2009, 09:07 AM
You don't? A dirty filter wont afffect running when the engine is under load? Lean running wont cause overheating? You going to change the fuel pump before the filter?
I guess I will bow out of this thread. I have nothing of value to add.

10-01-2009, 07:26 PM
You guys really know your stuff.
Today I put in a new fuel pump , after remembering that the filter and Oxygen sensor was replaced 6 months ago.

It instantly sounded different ( the fuel pump)
started right up , and i let it idle about 20 min and run PERFECT.

It used to pop and sputter after 1-2 min and then fade off and die.
I hope to give it a good workout tomorrow and make sure.

For almost 2 yrs its been popping on my longest days in the hot summer, so I sure hope this fixed it wow. must just have been worn and not supplying enough pressure.

Thanks so much guys! ...

now on to my 30 hp regular carbed engine with smart spark problems ;-)
left cylinder stops firing randomly , then suddenly kicks in and goes again.
I did remove the wires and clean them and blow the coils and smartspark unit out.. it has run good on wednesday. i just dont want to have the whole engine taken off to replace the coils..

also , for Oldtimer , yes I had one of the 1st EFI lazers and sold it with 4600 hours and was still running strong.
They really are great engines when they run.
I hope they put an EFI on a Next Lazer soon , so I can get an upgrade.

Two Seasons
10-02-2009, 02:54 AM
Sounds like your 30hp needs a new coil, if you are sure it's not a short somewhere that shorts only when you hit bumps.

Depending on whether or not the other coil was ever replaced, I'd replace them both while you are in there.

10-02-2009, 06:26 AM
yea i just had my coil done with inly 112 hours on a 2009 28 hp kaw.

after about 45 min of hard running the coil, if bad, will fail, sounding like a carb issue. it will run so bad it wont go up a small hill

10-02-2009, 02:03 PM
yea it goes out at very odd times, not predictable yet so far...
but My repair shop said same thing , to replace them both while its apart.

any time it stops firing on the left , so far i can turn off and after a few start attempts , it wiill run good again.

HALLELUJAH on the EFI!! it worked PERFECT today! hahahha I love when everything works good

10-02-2009, 05:02 PM
Why replace both? I was told to do it on Kawasaki's a while back but shouldnt be needed on a Kohler with the smart spark.

Or is this a Horizontal shaft engine that is a PITA to replace coils on in a lawn mower? Then I could see the reasoning....

If people want a horizontal shaft on a lawn mower at least leave the flywheel side accessible for service....stupid manufacturers.

10-02-2009, 05:46 PM
Yes its a horizontal shaft. and I don't think it could be that hard to make fly wheel accessible without ripping the whole engine off...

but yes thats the reasoning , since its such a pain to remove.

It sputtered once today a little bit then went like a hog again , so no rhyme or reason so far.

It couldnt have anything to do with carburation could it?

Two Seasons
10-02-2009, 07:27 PM
Maybe the insulation of the spark plug wires have broken down.

Have the measured the ohms of both? Someone else will have to be specific on the ohm value that you need, but I'd start there cause it sounds like a intermittent short to the coil.

10-02-2009, 08:23 PM
Are you sure it's losing spark, or do you just have the problem narrowed down to one side? You really need a special tester capable of testing a system that can produce 18kv. A loose conection from the SAM to the coil can make an engine run terrible. Did you put a timing light on it?

10-02-2009, 11:03 PM
well heres the test i did.

when it loses power, i pull the left plug wire and it runs excactly the same.
when I pull the right plug, it dies instantly.

but what else could it be? even if its sending no spark to left plug ,it would still be a bad coil, right?