I mowed the lawn about three hours late yesterday. I tucked it under the shelter and turned it off. Today I went to start it late. The starter motor turns fine, but the tractor won’t start. I am not familiar with JDs. It seems that the fuel does not reach the cylinders. There is a lot of fuel in the tank. Are there any switches, relays, or connections that I need to check? I haven’t had time to look much this afternoon.
Are you blowing a fuse? And the fuse blows as soon as the key is turned?
If both questions are yes, I think the problem is the temperature sensor. In the thermostat housing there is a temperature sensor that is connected to a two wire harness that goes to the injection pump; This is the “cold start advance” part of the system to make it easier to cold start by advancing the timing.
If you unplug the sensor and it works fine, do an ohms test to the sensor, it’s probably shorted.
The sensor in the thermostat housing controls the advance of the injection pump. When it fails, it makes a short circuit and blows the fuse. Try unplugging it, replace the fuse, and see if it starts and works. The part number is RE503242, (see photo) if you are changing quickly, you don’t have to drain the coolant, just make sure it is not hot at the moment. You’ll want a tray under the tractor to collect the coolant, so you don’t have to clean it up.
You may need to re-prime the fuel system, if it still won’t start.
In order to comply with exhaust gas emission regulations, the injection pump timing should be about 6 to 9 degrees before neutral. These timing values do not allow proper starting when the engine is cold. To facilitate engine starting, a cold advance system gives the injection pump a temporary over-timing.