Small Kohler engine problem

tracker1 · Feb 4, 2020

Looking for some help with my John Deere L130. Saw a forum topic on pluse fuel pumps here from 2013 and seems there are some experts on the forum.

I have an older JD with a twin Kohler motor. It's been running fine for the 4-5 years I've had it until a week ago. While mowing some undeveloped acres on a lake lot the engine just died out. I'd let it sit a few minutes then it would run again for a few minutes then die again. Runs great when cold, problem only happens when hot and running hard. I noticed the fuel filter was old & dirty so replaced it. But that didn't help. Yesterday noticed the new filter had no fuel in it when it died. I figured the pulse fuel pump had stopped working. Bought a new one and installed it, and when cranking it the fuel filter filled up immediately with gas and it ran fine. However in about 15 minutes it died again and filter was empty. Tried removing the gas tank cap to see if maybe it wasn't venting properly, but that didn't help. Once it cools down it will start again. Yesterday it was in the mid 70's while mowing.

Trailered it home and noticed the fuel filter was again filled with fuel and it started right up. Ran a compression test today have have 160 lbs in both cylinders. Any ideas on what's wrong or what other tests I can do?

hanovertom · Feb 4, 2020

You don?t say which Koehler. If it is a Command, good chance the magneto could is failing .

super99 · Feb 4, 2020

Kinda sounds like something is blocking the fuel from getting out of the tank. Have you looked inside the tank? Can you pull the tank off and clean it out?? Old fuel hose collapses when running, shutting off fuel flow?? Chris

Liquid_wrench · Feb 4, 2020

Maybe something in the tank or a fuel hose falling apart inside.

jackbrit3 · Feb 4, 2020

I once had a small crack in fuel line, and it would suck a small amount of air causing the fuel filter to run low.

MtMan · Feb 4, 2020

I know for a fact that in the older Kohler engines they had a problem with the valve stems getting carboned up and when the engine got hot it would shut down. I've cleaned many a valve stem with emery cloth and good to go for a long time again. Don't know if that's your problem or not . Kohler engines are a good engine I believe.

UncleTom · Feb 4, 2020

Does it have spark when it dies?

jeffcat · Feb 4, 2020

Another two cents thrown in. All of my mowers I use 5-20 synthetic blend oil.
It eliminates that carbon build up with straight dyno oil. Insides of the
engine stay sparkle clean. Been doing it for years.

Steve@Advance · Feb 4, 2020

I would replace the fuel lines, and if there is a fuel shut off valve or dual tank valve, replace it too.

Sounds like the pump is sucking air or a line is collapsing internally.

Any heat sources near the fuel system? Exhaust heat, hot air discharge?

tracker1 · Feb 4, 2020

It's a Command 23 Kohler model CV23S. I haven't checked spark when it dies but will next time. And have no idea about possible carbon build up on the valve stems. Since the fuel filter is empty when it dies I suspect it's fuel related. The tank is buried in the chassis so haven't pulled it yet, but was thinking of replacing the fuel line to the tank. I will replace all the fuel lines tomorrow, I know ethanol can be hard on them.

One question I wanted to ask is if it's possible when it gets hot the older engine can send the proper amount of vacuum to the pulse line that goes to the fuel pump?

Petert · Feb 4, 2020

I have had a few of the pulse fuel pumps go bad within a few minutes of run time.
Some last 20 years or more but some last just a few minutes ,just keep replacing with
new one until you get a good one. Does not matter if you buy a cheap one or an
expensive one they still go bad.

Good luck PeterT

TimV · Feb 4, 2020

Had a similar problem on a new-to-me engine recently. Engine would run good for a while then die. No fuel pump involved--just gravity flow. Replaced line, shut-off valve and filter with no improvement. Upon further troubleshooting noticed that I got very low flow even when I ran fuel straight out of the tank into a bowl held beneath the outlet with the tank cover off. Turned out the tank had an internal filter at the outlet and it was plugged nearly solid. With no way to eliminate it short of replacing the tank, another filter already inline downstream, and nothing to lose, I ran a small drill bit by hand up into the outlet and drilled through the filter. Reinstalled line and got full flow, and it's had 100+ hours of run time since with no further problems. Just something you might want to investigate before replacing more parts.

tracker1 · Feb 4, 2020

(quoted from post at 01:35:26 02/05/20) I have had a few of the pulse fuel pumps go bad within a few minutes of run time.
Some last 20 years or more but some last just a few minutes ,just keep replacing with
new one until you get a good one. Does not matter if you buy a cheap one or an
expensive one they still go bad.

Good luck PeterT

I've read about that about new pumps going bad quickly but since the new pump is acting just like the old pump I'm thinking that's not my issue. I did hook up a vacuum gauge to the pulse hose coming off the crankcase today and I can see the needle go up and down as the pulse comes in and out. I'm planning on taking the gauge with me next time I mow my lot and if it quits I'm going to hook it up and see if I get the same reading when hot.

tracker1 · Feb 4, 2020

(quoted from post at 01:45:44 02/05/20) Had a similar problem on a new-to-me engine recently. Engine would run good for a while then die. No fuel pump involved--just gravity flow. Replaced line, shut-off valve and filter with no improvement. Upon further troubleshooting noticed that I got very low flow even when I ran fuel straight out of the tank into a bowl held beneath the outlet with the tank cover off. Turned out the tank had an internal filter at the outlet and it was plugged nearly solid. With no way to eliminate it short of replacing the tank, another filter already inline downstream, and nothing to lose, I ran a small drill bit by hand up into the outlet and drilled through the filter. Reinstalled line and got full flow, and it's had 100+ hours of run time since with no further problems. Just something you might want to investigate before replacing more parts.

That's interesting. I tried blowing into the tank through the fuel line and can hear the air bubbling into the tank but it took some force. Maybe it's a combination of poor fuel flow from the tank that is further impacted by lack of engine vacuum when it's hot. Will go ahead and remove the seat, rear fender and tank tomorrow to see how it looks along with replacing the fuel line.

tracker1 · Feb 4, 2020

Here's what my fuel pump looks like. Fuel line hooks to top of tank.

jeffcat · Feb 4, 2020

Read about the filter in the tank. Same deal on Honda engines. Look down
inside your gas tank and you see a little ultra fine white plastic filter. You
need to take the tank off and the filter unscrews. They are cheep enough so
just replace it.

Stroby · Feb 4, 2020

I suspect there is a fuel line issue as well.....but a good dose of Seafoam won't hurt a thing and it will remove carbon buildup if that exists.

3000OH · Feb 4, 2020

This is a long shot, but might check that your in & out lines are
in exact same orientation as before you changed filter. I put
a pulse pump on a Tecumseh once and found the pump
output line had to be downhill from the pump to the filter to the
carb. Otherwise, air in the gas would coalesce into a big
bubble at the high point of the output line & the pulse pump
didn?t have enough oomph to push past it. Symptoms were
exactly like yours.

Have also heard some filters are gravity-only and not pump-
rated, so might check that, too.

John M · Feb 5, 2020

Oil level too high.

Mike M · Feb 5, 2020

Maybe try gravity feed from another tank and see if it keeps running ?

Determined · Feb 5, 2020

Have you checked the oil?

Some Kohler's have a sensor that will shut you down when the oil is low, hilly/rough terrain can cause it to shut you down sooner if the oil level is marginal.

JK-NY · Feb 5, 2020

I will go along with the other post that mentioned fuel lines. I
have had a couple of times gas flow issues on small engines
with the pulse type of fuel pump and the problem was that the
old gas line was dry rotted with very small external cracks
which would never leak gas but apparently would allow a
small amount of air to seep through enough so the pump
wouldn?t overcome it. I would also check fuel pickup in the gas
tank.

ztrmowers · Feb 5, 2020

when it dies make sure you still have fire,could be coil going out they will do that only after engine has been hot for while, try this get it running and just before its trying to die see if choking it helps if does then you have fuel issue, if not its usually in the coil

Fatamus · Feb 5, 2020

Fuel trouble is a good idea but as you were describing the issue it could have went either way between fuel and a coil going bad. Once the coil heats up it expands and if bad it could lose conductivity and when it cools down it shrinks and the connection could be reestablished. This only happens several times before the coil burn completely out. Had it happen on my Harley.

Then was driven an old International 5yd gas dump. Once I'd hit 4th gear it would die. I went through the distributor, valves, yada, yada, yada... it wound up being a small spruce twig in the gas line and when the fuel draw was high it would suck a twig into a sharp bend in the pickup tube and block the fuel flow. When the truck set along side the road for ten minutes the twig would fall back down the pickup tube and the truck would start and run until the fuel draw was high again.
I have also he seminar problems with small rock in the line and black tape in the tank.

Fatamus · Feb 5, 2020

(quoted from post at 07:58:17 02/05/20) when it dies make sure you still have fire,could be coil going out they will do that only after engine has been hot for while, try this get it running and just before its trying to die see if choking it helps if does then you have fuel issue, if not its usually in the coil

I like your response
Great mimes act alike

Tim Cl. · Feb 5, 2020

Yes, sounds like a magneto going bad. Same thing happens on a Briggs & Stratton

tech5201 · Feb 5, 2020

I wouldn't start tearing it apart yet to get to the fuel tank.
Verifying spark is simple.
In-line spark testers are cheap.

cuby · Feb 5, 2020

Had the same problem with my Cub cadet 2135 single cyl. I put a plate over where fuel pump was and installed a $6 electric fuel pump I found on the web. No more fuel problems.

IndianaSteve · Feb 5, 2020

The vent in the fuel cap is plugged

tracker1 · Feb 5, 2020

(quoted from post at 21:47:53 02/05/20)
The vent in the fuel cap is plugged

I did buy a new gas cap this week, but don't think that's the problem as why would it vent when cold but not when hot?

Really appreciate all the feedback! The oil level is on the money and both magneto coils were replaced last year. Spark plug color is perfect..... I really don't suspect a spark problem but will check that next time it dies.

I won't be able to test it out again until I take it out to my lake lot to mow. However I am thinking of pulling the tank and replacing the fuel line to ensure I don't have an issue there.

Fatamus · Feb 5, 2020

(quoted from post at 13:02:26 02/05/20)

(quoted from post at 21:47:53 02/05/20)
The vent in the fuel cap is plugged

Click to expand...

I did buy a new gas cap this week, but don't think that's the problem as why would it vent when cold but not when hot?

Really appreciate all the feedback! The oil level is on the money and both magneto coils were replaced last year. Spark plug color is perfect..... I really don't suspect a spark problem but will check that next time it dies.

I won't be able to test it out again until I take it out to my lake lot to mow. However I am thinking of pulling the tank and replacing the fuel line to ensure I don't have an issue there.

I think you are on the down hill side of this issue. While reading your updated post, I think you might be getting close. I have had rubber gas lines completely collapse or deteriorate on the inside and swell partially blocking fuel flow.
No matter what Good Luck.

IndianaSteve · Feb 6, 2020

(quoted from post at 22:13:15 02/05/20)

(quoted from post at 13:02:26 02/05/20)

(quoted from post at 21:47:53 02/05/20)
The vent in the fuel cap is plugged

Click to expand...

I did buy a new gas cap this week, but don't think that's the problem as why would it vent when cold but not when hot?

Really appreciate all the feedback! The oil level is on the money and both magneto coils were replaced last year. Spark plug color is perfect..... I really don't suspect a spark problem but will check that next time it dies.

I won't be able to test it out again until I take it out to my lake lot to mow. However I am thinking of pulling the tank and replacing the fuel line to ensure I don't have an issue there.

Click to expand...

I think you are on the down hill side of this issue. While reading your updated post, I think you might be getting close. I have had rubber gas lines completely collapse or deteriorate on the inside and swell partially blocking fuel flow.
No matter what Good Luck.

When the vent is plugged the engine runs until it uses enough fuel to create a vacuum in the tank. That's why it won't happen till its good and hot. I've had two engines do this. Actually just blew the vent out with compressed air and it was good to go.

Small Kohler engine problem

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