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Vapor Lock Issue

14K views 16 replies 9 participants last post by  ariensman2 
#1 ·
We talked about this in the past but never came to a solution at that time. I have the kohler 14hp in my machine and it appears to run out of gas and stall after about 20 minutes of hard use mowing. It will start right back up if I let it rest for a while and go for another 20 minutes or so depending on the outside temperature. This never happens in the winter plowing snow but that is a much easier task for the tractor. In earlier posts we talked about relocating the exhaust to point away from the machine thinking the heat may be causing a vapor lock. I have done that but it didn't help. It doesn't appear to be overheating and runs very well when cooled down. Does anyone have any ideas how to prevent possible vapor lock or any other ideas what it could be? It has always done this all along even the previous owner told me it did that.
 
#2 ·
Ck the gas tank cap for proper venting. If that's ok then I would consider an electric fuel pump. I got the idea from Brian Miller's pulling site. I have a similar issue with my Wheel Horse.
http://gardentractorpullingtips.com/carbfuel.htm
 
#3 ·
I think you might be right about the fuel pump. My vent in the cap looks ok and I have an inline fuel filter that I can visually see and its full of gas so fuel supply to the pump is fine. When I disconnect the outlet of the fuel pump it pumps big time but it possibly could be intermittant. I was wondering if I could just gravity feed the carb. I'm not sure why these engines have fuel pumps as the Briggs I have in other tractors are all gravity feed.
 
#4 ·
Next time it happens check for spark while it's still hot,
could be a bad coil.:fing32:
Vapor lock can happen,but a lot of stars need to line up for it to happen, and if yours is doing it that often it would be a little out of the norm.
 
#6 ·
Yeah it does it every time the engine is using the governor and working as hard as it possibly can and that is only when mowing. It does also sound like it could be spark too because it gives no warning, it just starts to sputter a little and the RPM goes down and down and then it just stops.
 
#7 ·
I agree with John on this one, go after the coil. I have run my 1980 2414 without the fuel pump with out any issues. The tank is a bit higher than the carb, so you can never empty the tank. The 1965 2412 with the L shaped tank was higher than the carb and it didn't have a pump, never had any issues. Learned this the HARD way. Always put a filter between the tank and the pump and another filter between the pump and the carb. On an old pump, it flakes small bits of rubber and not let the float seat and causes flooding.

Coil getting hot will open or it will sputter and loose spark, sounds like it ran out of gas, then open. Let it cool and it starts right up, runs fine. Next time it happens and you are running battery/coil ignition, feel the coil and see how hot it is.

BUD
 
#8 ·
I will check my coil for heat next time. Still wondering why it only happens when mowing and the governor is always kicked in. The governor never activates when just plowing snow. Would just the air temperature cool it enough. It seems like the temperature around a warmed up engine would always be the same any time of year. I really think the 60" mower is just too much for a 14 hp single cylinder motor. It works it so hard that sometimes I think its going to blow but then it stops and I have to let it rest. Other people have these with no problems. I also just rebuilt all the spindles and greased them up and everything spins freely.
 
#9 ·
Dave,

I'm wondering if it could be the plug?? I recall reading on one of the sites that there is a standard plug and "heat"plug. If the plug gets too hot, you lose some spark and shuts the engine right down. Once it cools, it is ready to roll again. I had a plug in mine that showed spark but wasn't enough to keep it running. Just a thought and may be a cheap fix.
 
#10 ·
You've got me thinking now. I used the plug recommended by kohler original equipment so maybe I should just get a new one and see what that does. Is this "heat" plug a cooler range plug for hot running engines or a hotter range plug for cold blooded engines?
 
#13 ·
I agree with the other posts that are pointing to the coil as the culprit. I know you looked at the fuel filter and all looks ok. I just wanted to point out, fwiw, that if a paper filter ever gets water in it, it will never pass fuel well again, if at all. This is just a tidbit of info I have picked up during my 40 years of small engine experience.
 
#16 ·
I checked the coil today when it died and it was nice and cool. I replaced the plug but no change. This time I was watching the see through fuel filter closely and noticed the filter would fill up and drain out then the engine would stop. Then I loosened the hose clamp on the hose at the pump and the filter would fill right up. It appears to be a fuel pump issue as mentioned by Mike above. Just not sure why this only happens when its hot out. I took the tank cap off just too make sure the tank was venting properly and no change. I checked the tank outlet and all was clear. no junk in the tank and free flow when I pull the hose off the carb. I will try to bypass the fuel pump and see how that works. I couldn't go any further today as the mower mule drive assy. broke. Just part of owning a PK. If you use them they will break down.
 
#17 ·
Well guys, I have the prognosis. It was the fuel pump. I bypassed it using just gravity feed and mowed today for an hour and a half and it never missed a beat. The fuel filter appears to stay at least 3/4 full most of the time. The pump still worked well and shoots out gas big time but it just appears to vapor lock or something and can't pull fuel through. Thanks for all your input.
 
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