View Full Version : Clogged Vacuum Line for Fuel Pump

05-01-2010, 11:29 AM
I am hoping I can get some help from anyone here who has experienced this problem.

I have a Kohler 20hp (older engine).
When I got the mower it ran fine until I unloaded it off my trailer.

Since then I have replaced the fuel pump, all fuel hoses/filter, carb gaskets, spark plugs, air cleaner, Oil/Filter, and other items not related to the engine.

Its a pain in the arse to start up unless I use a little bit of starting fluid or fuel splashed in the carb. Then it runs fine and strong.
After about 15 minutes it will die and not restart. I know the problem in that the pulse vacuum line gets clogged up with Oil. I will drain the oil from the line and then it starts right up unless its been sitting for a few days then I have to use started fluid.

I know that the Oil is not overfilled since the dipstick shows up oil at the bottom where the safe zone is.

What could be causing this?

Thanks in advance.

05-01-2010, 11:40 AM
Excessive crankcase pressure. I've never heard of such a problem, but it is possible {I guess)

05-01-2010, 12:31 PM
Is the crankcase breather clogged?

05-01-2010, 12:54 PM
I will have to check and see if its clogged when I get over to the mower tonight.

05-01-2010, 11:38 PM
not clogged. It is still dieing out on me after about 10 minutes. The vacuum line still clogs up with oil
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05-02-2010, 12:45 AM
I seen this one time years ago. There was a crack in the sump plate and oil from the main bearing on the crankshaft was being pumped into the outlet for the pulse line. In the end I plugged off the pulse line and went with a fuel pump that mounts on the rocker cover. I will try to get you the part number for what I think may fix your problem

05-02-2010, 01:08 AM
I did not make the edit time limit. It is about $100 for the kit. Not cheap
Here is the number for the rocker cover fuel pump I was talking about.

24 559 10-S* FOR CH18-25/730-740

* Integral valve cover. For #2 cylinder side (oil filter side) only. For engines
below Serial No. 2520800017, also order Valve Train Kit 24 755 66-S to convert to
compatible rocker arms.

Recheck by using your engine numbers before ordering it just to be sure

05-02-2010, 10:54 PM
Thanks for all your help!

piston slapper
05-03-2010, 02:57 PM
ricky86 is probably right. If you're pumping oil into the fuel pump pulse line, you have crankcase pressure. Going to a manually operated fuel pump will get it to stay running, however, the engine is going to continue to use oil.

Possible reasons for crankcase pressure on Kohler's :
Reed Valve broken
Leaking Head Gasket
Cracked Piston Ring
Restricted Crankcase Breather

Keep an eye on your oil usage or you might lose the engine

05-03-2010, 03:19 PM
I just went and bought a 2-3.5psi electric fuel pump and will use that.
Going to plug up the pulse vacuum line and will probably check the oil level right before I use it.

05-03-2010, 03:27 PM
Also to add. It doesn't burn any oil. Even when I first start it up there is no blue smoke.
The exhaust smells normal also and runs decent when it does run.
It bogs going up steep hills though so it might be the lack of fuel going in that might be causing the excessive bogging.

Hopefully this will work and I can use it for backup when need be.