John Deere LX188 carb vent overflowing

[ILENGINE]

FYI Kawasaki FC540V single Cyl. on lx186.. had lots of odd running intermit problems, with gas leaking from overflow tube behind carb, sometimes a lot, other times seemed to work with out leaking.. ended up being bad float(plastic).. tried to repair by drilling hole draining drying, etc. then resealing, but didn't use the correct sealant?? bought new float $25+~ and working fine since., approx 1 year. If had to do again would have tried sealing with JB Weld, maybe would have saved a few $$ as i have repaired Plastic Radiator tanks, etc. and worked great.

I have used a hot glue gun in a pinch for plastic floats. Gas doesn't soften the hot glue. Repaired a float on a customers generator 3 years ago, during a week long power outage following an ice storm. Genny is still running without issue.

 

[fcctucke]

Hi all,

I've got an LX188 with the Kawasaki FD501V. I recently noticed after shutdown fuel coming from the bowl vent on the top of the carb. This explains the mystery fuel smell I've had for a few months now. I took the carb apart and it was surprisingly clean inside. The float needle however did show some slight wear on the sides and I suspected maybe it was sticking in the needle bore and not seating properly hence the overflow. So I ordered a carb kit from the dealer, replaced all the components in the kit including a new needle. Fired her back up, warmed her up thoroughly and low and behold it leaked(overflowed) again a few seconds after shutdown. I've checked the vent hole on the fuel cap to make sure it wasn't holding pressure or any sort of vacuum and that seems to be working fine. Is there anything I'm overlooking such as maybe fuel line routing(siphoning effect)? I'm very familiar with carbs of all sorts and I'm starting to think that possibly the seat is simply worn in this carb and maybe I'm due for a replacement carb. Any thoughts or suggestions are greatly appreciated.

Thanks,
Bill

Hi Bill,

Have you checked that the fuel shut off solonoid is operating correctly? There is no way for the fuel to enter the carb if the shut-off solonoid is in the off position. When 12V supply to the shut-off wire is removed by the key the spring-loaded solonoid pushes a tapered point into the inlet. John Deere provided this extra function to prevent backfires.

,Fred

 

[PJ]

Hi all, I've got an LX188 with the Kawasaki FD501V. I recently noticed after shutdown fuel coming from the bowl vent on the top of the carb. This explains the mystery fuel smell I've had for a few months now. I took the carb apart and it was surprisingly clean inside. The float needle however did show some slight wear on the sides and I suspected maybe it was sticking in the needle bore and not seating properly hence the overflow. So I ordered a carb kit from the dealer, replaced all the components in the kit including a new needle. Fired her back up, warmed her up thoroughly and low and behold it leaked(overflowed) again a few seconds after shutdown. I've checked the vent hole on the fuel cap to make sure it wasn't holding pressure or any sort of vacuum and that seems to be working fine. Is there anything I'm overlooking such as maybe fuel line routing(siphoning effect)? I'm very familiar with carbs of all sorts and I'm starting to think that possibly the seat is simply worn in this carb and maybe I'm due for a replacement carb. Any thoughts or suggestions are greatly appreciated. Thanks, Bill

Yes the seat could be warn or the float and needle adjustment could be be insufficient. Has the needle got a rubber tip?

PJ

 

[Ohsoblue92]

I'm kind of new here but would a simple inline fuel cut off valve placed before the carb solve the problem?

 

[PJ]

I'm kind of new here but would a simple inline fuel cut off valve placed before the carb solve the problem?

Sorry I have not got info on this mowers carburetor lets see if some of our older hands has a answer.

Regards
PJ

 

[jakeamondo]

found this article

PostPosted: Wed Apr 15, 2009 6:12 am Post subject: Re: LX188 Kawasaki FD 501V carb issues
I spoke to Steve at Mikuni America-the carb maker. He advises me that if the float needle were worn, fuel would come out of the overflow tube at the top.

He advises me to place a new float bowl O ring and remove the fuel injector cleaner gas in the tank and fill with fresh gas.

There is a pilot fuel jet in the top of the carb which he also advises cleaning.

However in my opinion the fuel solenoid valve would have to be stuck in open position. Test solenoid with 9 volt battery, positive to terminal, negative to ground. you should here it click.

 

[arch252]

Sorry to resurrect on old thread. I have an FD590V on a JD345. I cleaned the carb and it is running amd idling great but gas is leaking out of the vent tube on top of the carb while it is running. It will start and stop overflowing while in high idle but pumps out the overflow heavily when reduced to low idle. Is that a needle valve seat / float issue or something else? Not leaking after engine is shutdown, only while running.

 

[bertsmobile1]

Hi Bill,

Have you checked that the fuel shut off solonoid is operating correctly? There is no way for the fuel to enter the carb if the shut-off solonoid is in the off position. When 12V supply to the shut-off wire is removed by the key the spring-loaded solonoid pushes a tapered point into the inlet. John Deere provided this extra function to prevent backfires.

,Fred

You are wrong with this one.
The shut off prevents fuel going through the main jet.
It does not stop fuel entering the carb. It is designed to stop fuel entering the engine in the few revolutions after you kill the engine and flowing unburned out the exhaust because the kill switch shuts off the spark.

What is happening here is the float valve is not holding back the fuel after shut down so the fuel bowl overfills and fuel flows out of the AIR VENT on top of the carb.
Nothing is flowing through the main jet.
I have come across this problem when gravity fed carbs have been used to replace fuel pump carbs because the float does not have enough closing force to to overcome the pressure from the fuel pump.

 

[bertsmobile1]

Back to the original problem.
I rather think you have a small hole in the pump diaphragm this is allowing crankcase pressure to over pressureize the fuel line and lift the float needle and push fuel out the overflow.
The other possibility is the heat from the engine is heating the fuel in the bowl & either boiling it or just expanding it enough to overflow when then engine is off and there is no cooling air flow.
Last thought is bad fuel tank vent over pressureizing the fuel lines after shut down again lifting the needle. Remove the fuel cap when you finish mowing to check this .

Try putting an inline fuel tap between the pump and the carb.
A band aid solution but it should stop a pressure problem.
If it still overflows then it will be a heat problem.

 

[arch252]

It will ovreflow fuel from the top vent tube immediately upon starting so that's not the problem. I replaced with fuel pump and no changes so rule that out. I had already checked the vent hole on the gas cap, that was one of the first things I did.

So, having ruled all that out, can this be a worn needle valve not seating? The fact that the overflow really comes out much more when it's idled down would seem to support this.