1991 7.3 IDI F250 bush truck

[WallyS]

Been browsing the site for a while now, trying to diagnose a problem with this truck. I'm not sure where to start explaining the previous owners wiring.

When I got it, it had a push button start as it wouldn't start with the key, power to the cab, all lights work, etc, but no crank. The push button start is an extension cord jumping the solenoid to a button in the cab, awesome... Glow plugs were not functioning, they are brand new, along with a new oem starter. The original gpc was not fiddled with, and the po suspected either a gpr or the controller so I went ahead and bypassed the gpc (following the guide on this site) and replaced the relay because I am a cheap ******* and in the middle of nowhere.

Some numbers:
11.7v on the S & I terminals on the GPR KEY ON
12.2v on the hot side of the GPR KEY ON

I don't have anyone around right now to help me test the GP voltage.

Do these numbers seem low? I am thinking the problem lies somewhere between the GPR and ignition switch or from GPR to the glow plugs themselves. There were two grounds that were not connected (one on the starter solenoid and one from under the GPC somewhere to the hood of the truck. I hooked them up, no change.

The batteries are also brand new, but the cables are quite shabby.

Starts fine on ether.

Any advise on troubleshooting from here?

 

[franklin2]

Do you hear the relay click when you ground the terminal where the white wire was?

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[WallyS]

Do you hear the relay click when you ground the terminal where the white wire was?

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Yes.

 

[WallyS]

I grounded it for 10 seconds, cranked her over and it barfed to life! It's about 5 deg. C. here. Pretty stoked to hear it run. So now what? I'm thinking bad ground to the switch? It's my birthday and I have treated myself to a bottle of rye, so needless to say I wont be working on the truck anymore today. Thank-you franklin! :cheers

 

[franklin2]

Most people just take the white wire off and tape it, and then hook their own wire to the terminal where the white wire was, run it through the firewall, and hook it to a pushbutton switch. Then hook a ground wire to the other side of the switch. Eliminates a lot of headaches. If I were to guess, your messed up ignition switch wiring might be part of the problem that the controller is not working correctly. But there are lots of other possible reasons also, and that's why the manual switch is the sure-fire way to get the truck to start reliably without the bother with all the other stuff.

 

[WallyS]

Most people just take the white wire off and tape it, and then hook their own wire to the terminal where the white wire was, run it through the firewall, and hook it to a pushbutton switch. The hook a ground wire to the other side of the switch. Eliminates a lot of headaches. If I were to guess, your messed up ignition switch wiring might be part of the problem that the controller is not working correctly. But there are lots of other possible reasons also, and that's why the manual switch is the sure-fire way to get the truck to start reliably without the bother with all the other stuff.

I had the switch hooked up wrong, I used a toggle switch that was laying around, wired it to the the acc terminal not the ground. Went to town and picked up a push button switch, works great! Now onto fluid changes, engine oil looks terrible. Thank-you.

 

[franklin2]

I had the switch hooked up wrong, I used a toggle switch that was laying around, wired it to the the acc terminal not the ground. Went to town and picked up a push button switch, works great! Now onto fluid changes, engine oil looks terrible. Thank-you.

As soon as you put the new oil in and run it for 30 minutes, stop it and look at the oil again. It will look as black as it did before. Diesels turn the oil black.

 

[WallyS]

It's actually a bit grey and sludgy, hopefully from condensation from sitting so long since I bought it. Going for a long ride to heat things up then will do my oil change.