Please Help! My B7800 is blowing a fuse, shutting down. Tractor stuck outside :-(

[easygo]

My B7800 is 13-years-old with 1100 hrs. The tractor shut down after I used it for two hours. I found the 5 Amp fuse that protects the key switch was blown. I replaced fuse, turned on the engine and it shut off after a couple of seconds. Same fuse blown. The third fuse didn't even operate the fuel shutoff solenoid, but blew as soon as I tuned the key.
I unplugged the fuel shutoff solenoid and replaced the fuse again. It didn't blow, so I thought I found the bad part.

Off to the dealer, bought new solenoid and a fuel relay, there goes $100. Replaced both and the tractor started right up. It ran fine for 10 minutes than started sputtering as if only running on 3 of the 4 cylinders. Sounded like the engine was not getting enough fuel. Eventually it shut off and now it is blowing the same 5 Amp key switch fuse again.

I have an old battery. Could the low voltage cause some isse like this?

It is rather cold here (-8 at the moment) Could that be causing any issues with the electrical system?

It is not the fuel. I use Power Service in every drop of fuel that goes into the tractor.
Any pointers would be greatly appreciated.

 

[diesel85]

It's probably a wire with the insulation worn and grounding to the frame.

 

[LouNY]

If you need to move it, disconnect the solenoid and physical move the shutoff to the run. But it sounds like you have a wiring problem to the key or from the key to the various relays or lights. Without a good wiring diagram it will be difficult to determine where or what.

 

[easygo]

I forgot to mention. The lights and the hazard flashers both work. The safety switches are ok to the best of my knowledge.

 

[Fallon]

Trace out the wiring on that circuit & look for a short. It could be a bad switch too, but less likely.

A bad ground would cause things to not work, but wouldn't blow fuses.

 

[sixdogs]

Have you searched this site for anything similar? I recall a mention of something like this before.

 

[easygo]

If you need to move it, disconnect the solenoid and physical move the shutoff to the run. But it sounds like you have a wiring problem to the key or from the key to the various relays or lights. Without a good wiring diagram it will be difficult to determine where or what.

Thanks LouNY. Unfortunately the solenoid moves something inside the injector pump area and there is no way I can manually set that to run.

 

[easygo]

Have you searched this site for anything similar? I recall a mention of something like this before.

That was the first thing I did. I found threads about no start issues, but none that listed a blown key switch fuse as part of the problem. Most were related to bad safety switches on the tractors. I wish mine was having symptoms like that. At least I would know where to start looking.

 

[Leejohn]

For a short I would check for a bare wire were the harness goes from fire wall to engine. The harness is real tight there and hitting the bell housing.

 

[fishpick]

I had a wire get worn bare under the tractor by the fuel pump that would short and kill the switch every time i tried to crank it...
electrical tape got me back to the barn...
paint on electrical tape solved it for good...