# JD GX345 Fuel Issue



## lonnyb_98 (May 20, 2012)

Recently my GX345 started to die after about an hour's use. Starts fine and runs great then after about an hour it will sputter and start to die. I first thought it was the TRM, which I have replaced several times, but this is different. When it starts to sputter, I choke it and it comes out of it.

I noticed in the fuel filter there is barely any fuel present, so I change the fuel filter, no change still sputters. I then changed the fuel pump assembly, UC18349, just north of the fuel filter. Same issue. There is still very little fuel in the filter at WOT. Is this normal?

I have seen that there is also another fuel pump assembly just below the carburetor, but my unit doesn't have one. Looks like there is a spot for one with predrilled holes but it's not there. Wondering if different serial numbers have anything to do with it missing? Other than the holes to mount the casting on the engine is closed off.

Thoughts?


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## BigT (Sep 15, 2014)

Hello lonnieb98, welcome to the forum.

The first thing we always mention is the fuel cap vent. If this vent is plugged, the tractor will run for a given time until vacuum builds up in the fuel tank and prevents the flow of gas. Check it out if you haven't already.

The next thing I would do is (carefully) blow back into the tank by mouth or with compressed air. If you use compressed air, remove the cap so you don't rupture the tank, and protect your eyes and face against a potential sudden release of gas.


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## Bob Driver (Nov 1, 2017)

The advantage of running clear vinyl motorcycle fuel line going into the carburetor is that you can see the fuel flow. As a routine, whenever somebody brings me an engine that starts fine, but then "sputters and dies" after any length of run time (5 minutes to an hour), I install a section of clear vinyl motorcycle fuel line going into the carburetor and in-line spark tester(s) and run it until the problem develops.

Low or no fuel flow through the clear line takes me in one direction in the diagnostic path, weak or lost spark takes me in another. You've got to know which path to take, otherwise you just end up guessing and chuckin' parts at it. Uninterrupted Air, Fuel, and Spark.... It's designed to run and stay running, until you no longer have one of the three.

"Bumping the choke" and it comes out of it, indicates the problem is highly likely a fuel flow problem. Now you have to know is it on the pressure, or vacuum side of the fuel pump. Another piece of clear vinyl fuel line between the pump and fuel filter answers that question. The advantage of running clear vinyl motorcycle fuel line is that it stiffens with age and contact with ethanol fuel, traditional rubber fuel line softens and can collapse under the vacuum draw of the fuel pump.

As Big T stated, you wouldn't by any means be the first guy bitten by a clogged fuel cap vent, or possibly a fuel hose clamp that is allowing air to be sucked into the vacuum side of the fuel stream around an ethanol softened rubber hose. If your fuel filter isn't almost completely full when it's sitting level, it's a strong indication of a weak vacuum draw from the fuel pump. Even a fuel tank that is mounted below the level of the carburetor bowl has some positive "head pressure". If you want to know how much, pull the fuel line off the inlet side of the fuel filter and you'll quickly get an answer


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## lonnyb_98 (May 20, 2012)

I will try cleaning the fuel cap.

Also, thanks for the advice on the clear fuel line. I will also be looking into that.


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