Electrical short in fuel delivery system (John Deere 5310)

sgiesecke · Aug 17, 2023

Tractor quit while I was mowing a field; it's stuck out there now. Lots of fuel in tank, cranks but doesn't start. Checked (bled connections) for air lock at every point. Fuel supply issue: fuel is getting to the fuel inj pump but is not coming out of it. At first I thought maybe the pump is bad; but the 20A fuse (in main fuse block) for the fuel shut off solenoid keeps blowing...went through four fuses, they burn immediately upon trying to start the engine. So, it appears I have a short in the wiring for the fuel system which burns the protective fuse and shuts off the fuel inj pump: resulting in no fuel to engine.

Where/how do I look for the electrical short? What tools (e.g. 12 vdc light) do I need? New to this. Thanks

WranglerX · Aug 17, 2023

I would check visible wiring between fuse and solenoid, if nothing obvious, might unplug wiring from solenoid, it would pretty much eliminate problem with wiring when you replace fuse and it does not blow with solenoid disconnected ...

thepumpguysc · Aug 18, 2023

Disconnect the cold start solenoid.. either on the bottom of the injection pump or at the rad. filler neck

JD5210 · Aug 18, 2023

As already stated by another person, I believe the problem is the thermistor sensor (thermistors are temperature variable resistors used as sensors.). On the thermostat housing there is a sensor that is connected to a two wire harness that goes to the injection pump; this is the "cold start advance" portion of the system so it starts easier when cold by advancing the timing.

When the sensor on the thermostat housing fails it shorts out and blows the fuse. Try unplugging it, replace fuse and see if it starts and runs. The part # is RE503242, if you are quick changing it, you don't have to drain the coolant, just make sure it's not hot at the time. You will want a pan under the tractor to catch the coolant, so as not too have to clean it up.

To comply with the exhaust emissions regulation, the timing of injection pump should be around 6 to 9 degrees before TDC. These timing values do not allow proper start-up operations when engine is cold. To ease engine start-up, a cold advance system gives to the injection pump a temporary over-timing.

When coolant temperature is below 50 C (122 F), the solenoid valve is activated and opens the cold advance circuit.

JodyLarrow · Jul 3, 2025

I know this is an old thread but I just wanted to say THANKS!, especially to JD5210 and thepumpguysc.
Thought I had it when the fuse was good when the wire was disconnected. I only found this thread after replacing the fuel shut-off solenoid ... and still blowing the fuse.
This turned out to be my exact issue. I sure wish they would've put a separate fuse in that loop if they insisted on powering it off the solenoid terminals!
A new RE503242 has been ordered.