Problem with John Deere 5105

[Bennie Norton]

My tractor would not start this morning. I had not replaced my battery since it was bought seven years ago. I assumed it was a dead battery. After purchasing a new battery, I discovered it was blowing the ignition fuse each time I tried to start the tractor. Does anyone have any suggestions?

[JD5210]

I believe the problem is the thermistor sensor. 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.

You may need to re-prime the fuel system, if it still does not start

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.

URL to JD parts
jdpc.deere.com/jdpc/servlet/com.deere.u90490.partscatalog.view.servlets.HomePa geServlet_Alt

[Bennie Norton]

Thanks for the help, the problem is now resolved.

[twinklez]

JD5210 I want to thank you for saving me hundreds of dollars on repair at a dealer. My 5105 would not start. My boyfriend and I thought it was because he had run it dry of fuel. He tried to prime it to no avail, and he had done this successfully twice before. We bought new fuel filters and tried to prime again. We loosened the injectors to see if fuel was reaching the injectors - it was not. We could hear the fuel draining back into the tank from the injector bypass line. My boyfriend thought then maybe there was a problem with the solenoid on the injector pump, so he checked the fuse. Fuse was fine. He stumbled onto one of your threads in another forum helping some poor fella who had been told by a dealership tech to remove his injector pump or injector or something and now he had to retime. We went back out again and fiddled and examined the fuse box at which point he discovered that there was a blown fuse, and that he had been looking at the secondary fuse diagram for our model. I think the fuse that blew was the key switch. I remembered seeing a comment in the post we had read about the injector pump that mentioned a blown fuse and we went back and reread your post. After almost 4 months of my tractor not running, I was standing in the kitchen getting pouring coffee before work when I heard the sound of a diesel engine outside and saw my boyfriend sliding across the front porch like Tom Cruise with delight. He had disconnected the sensor on the thermostat housing, replaced that blown fuse and turned the key. That day he went and bought a replacement sensor. The guy at the dealership says to him, "You know this little thing will keep your tractor from starting?" I had been in the process of saving my pennies (and nickels) so that I could pay the dealership to come pick up my tractor and fix it. I can't imagine what the cost would have been. Your post on this very common problem with my JD saved me money and likely saved my relationship. Thank you very very much for sharing your knowledge on the tractor forums.

[dclynch]

I had nothing to do with it but isnt this forum awesome. You can learn alot by just listening (reading) to these guys

[JD5210]

Twinklez, glad you to hear you got it running. Thank you for the note, it made my day.

Hats off to both you and your boy friend for not giving up on your tractor and continuing to work to get it fixed, good job!