# Kohler 18hp dies at full throttle



## GeauxCajuns82 (Mar 6, 2013)

I was recently given an 8yo Poulan lawn tractor that was sitting idle for about 2 years. The engine is a Kohler 18hp model #CV492S. I took apart the carburetor, cleaned everything, and replaced the gaskets and float needle. I also replaced the fuel line and filter. So I put everything back together, gave it a fresh tank of gas and new battery and tried to fire it up. Took forever to finally turn over but when it did it would not stay running at full throttle. It idles beautifully and even stays running when choked but will not go at full throttle. There doesn't seem to be any leaks.

Any ideas what could be causing this? Vacuum leak? Clogged jet?

One other thing: There is an inline filter between the tank and carb but I'm not sure it's original equipment. I replaced it with a general inline filter roughly the same size with connections for the same 1/4" hose. I also noticed that there is an air bubble in the filter. Are these supposed to be liquid packed?

-Matt
Lafayette, LA


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## paulr44 (Oct 14, 2008)

1. Fuel filters don't necessarily fill up with fuel even though they're working properly.
2. The fact that it sat for 2 yrs., it's a given there was, and may still be gum in the carburetor. If choke helps it run better, than the main jet is most likely restricted.
3. If you want to check the fuel pump, pull the spark plug, ground the wire, pull the fuel line from the carb. and put it in a coffee can and crank the engine over for 15 seconds. You should get 1/8 to 1/4 a cup min. An old automotive rule of thumb was 1 Qt. per minute...but these smaller engine obviously don't require that much volume.
4. The main jet should be above the anti-dieseling solenoid. At least the spec. for EHP I brought up shows it having a solenoid, else it's the bowl nut itself.


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## GeauxCajuns82 (Mar 6, 2013)

The engine does not have a fuel pump but there is a solenoid in the bowl. And now that I think about it, that's one part of the carb that I paid the least attention to when spraying with carb cleaner. I replaced the rubber plunger but didnt really get into the opening. I will try that tonight and let you know how it goes. 

Thanks for the help.

-Matt


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## GeauxCajuns82 (Mar 6, 2013)

Update: Yesterday I took apart the carburetor and cleaned out all the passages with carb cleaner. I noticed the bowl had a little residue that had perhaps dropped out from the initial cleaning a few weeks ago. I stuck the straw in all the jets and gave them a good spray to make sure they were clean. I fired it up again after I reassembled everything and it runs a little better (doesn't die at full throttle) but still doesn't run right...the speed keeps cycling and isn't smooth. Could it be that the mixture isn't set right? I didn't touch the screws when I cleaned everything off and it ran fine a few years ago prior to sitting for a few years so I don't see why anything wold have changed. Or could it be that the main jet is still slightly clogged?


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## RKDOC (Jun 20, 2006)

One thing I have found is that with Kohler engines you need to use a Kohler inline fuel filter. I can't explain why, and it doesn't make sense that another filter won't work, but I know I have solved fuel issues on Kohler engines with a Kohler filter. Best of luck


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