Fixing a jimmy rigged electrical system

[jfrancom101]

So I'm attempting to get my truck running, 1985 2500. It was diesel, but converted over to a 5.7. When I fist bought it it needed some carb work, (It did start up but was running horribly) After doing the work all the sudden the key doesn't do anything.
Whoever switched it over tp a 5.7 jimmyrigged some of the wiring and I found a look wire(Blue in the picture) Following the blue wire it connects to a yellow which goes to the distributor, and a red which goes to the fuel pump. When the key did nothing I connected the loose wire to positive on the battery and the ignition lights came on, however it wasn't turning over. Any ideas as to where this wire should go? I couldn't find any loose wires, I wondered about the solenoid looking thing (Also shown in the picture) but when I connect to to the other bolt nothing happens.

Also quick note, the truck still has 2 batteries because it used to be a desiel

 

[SirRobyn0]

Unless someone comes along that happens know what wire your talking about, you might not get a lot of responds. You can hit up here https://www.gmsquarebody.com/threads/complete-73-87-wiring-diagrams.53/ And look for wiring diagrams for your truck, but if it's been converted from diesel to gas and the wiring has been hacked, you may end up on your own tracing wires and figuring out where things go by doing that. Hopefully the diagrams will help.

 

[jfrancom101]

Unless someone comes along that happens know what wire your talking about, you might not get a lot of responds. You can hit up here https://www.gmsquarebody.com/threads/complete-73-87-wiring-diagrams.53/ And look for wiring diagrams for your truck, but if it's been converted from diesel to gas and the wiring has been hacked, you may end up on your own tracing wires and figuring out where things go by doing that. Hopefully the diagrams will help.

I'll take a look. And Thanks! I appreciate it! I guess I mostly thought maybe someone would know what the wires need to go to, even though it's jiimyrigged someone that's a better mechanic then me might have an idea. But those diagrams should help. Thanks

 

[SirRobyn0]

I'll take a look. And Thanks! I appreciate it! I guess I mostly thought maybe someone would know what the wires need to go to, even though it's jiimyrigged someone that's a better mechanic then me might have an idea. But those diagrams should help. Thanks

Well I've got 30 years as a mechanic, and the shop I currently run, we see a fair number of old squares, I'll try to help you in anyway I can, but without being there with you I just don't know. Those wires don't look like factory runs, but hey someone might see your pictures and go hey I know.

Obviously your starter has 12 V at the big terminal off the battery and get 12V to solenoid when you turn the key to crank.

You might check to make sure everything is clean and tight at the starter. You might see if you can either jump across the starter terminals, or run a wire from the positive to the small terminal of the starter and see if it cranks. Then check the fusible links by the starter. That solenoid looking thing does not look like a factory part, to me it looks like a Ford starter relay, but we really don't see very many diesels at the shop so if it's left over from then, I could be wrong about that.

 

[WP29P4A]

The Ford starter relay is most likely for the dual battery setup, not sure what they use it for but have seen them on several dual battery systems. As far as the blue/red/yellow wire, splice. If the red wire goes to the fuel pump (as it shows in the pic) and the yellow wire goes to the distributor, I does not make sense that someone would power the fuel pump off the distributor, so logically the blue wire would need power to supply the fuel pump and the dist(if there was logic involved in the wiring changes). Do you have a test light? I would document where you have power before you make any changes.

It's obvious that the red wire to the aftermarket fuel pump and the blue wire are not original, not sure about the yellow. Can you get a pic of the wires attached to the dist? Been trouble shooting electrical issues for the last 44 years on a daily basis, shouldn't be a problem helping you get your power back where it should be, just need good pics and some voltage readings. A test light would be good, a multi meter even better.

 

[75gmck25]

I think the external soleniods were used as a cheap way to charge dual batteries. You can even buy some that are rated for continuous duty (stock Ford solenoid is not).

My SBC truck has factory dual batteries, and the factory relay for the 2nd battery is pretty light duty. It just connects the charge wire to the battery when the truck is running, but it does not control power to any thing else in the truck/camper.

 

[SirRobyn0]

Perhaps my wording should have been better. Ford style solenoid. I did think about the duel battery thing but wasn't sure, as I'm much less familiar with the diesels and did not want to tell him the wrong thing.

 

[jfrancom101]

The Ford starter relay is most likely for the dual battery setup, not sure what they use it for but have seen them on several dual battery systems. As far as the blue/red/yellow wire, splice. If the red wire goes to the fuel pump (as it shows in the pic) and the yellow wire goes to the distributor, I does not make sense that someone would power the fuel pump off the distributor, so logically the blue wire would need power to supply the fuel pump and the dist(if there was logic involved in the wiring changes). Do you have a test light? I would document where you have power before you make any changes.

It's obvious that the red wire to the aftermarket fuel pump and the blue wire are not original, not sure about the yellow. Can you get a pic of the wires attached to the dist? Been trouble shooting electrical issues for the last 44 years on a daily basis, shouldn't be a problem helping you get your power back where it should be, just need good pics and some voltage readings. A test light would be good, a multi meter even better.

Yeah I got a picture right here. It's a little bit of a mess of wires but on the back it has the threes wires from the distributor cap going to the distributor itself. then on the right there is the yellow and red wires joined together with electrical tape. That yellow wire is the one going to the fuel pump. I went out with the multimeter. I have 12+ volts in both batteries, and on the connections as well. Not getting any reading from the the wires either except on the solenoid it has the small wire hooked up to the bolt, and it is grounded. and the on side of the solinoid is 12 volts positive, but not on the other side (I assunme you have to trip the solenoid for the power to get across)

 

[jfrancom101]

Well I've got 30 years as a mechanic, and the shop I currently run, we see a fair number of old squares, I'll try to help you in anyway I can, but without being there with you I just don't know. Those wires don't look like factory runs, but hey someone might see your pictures and go hey I know.

Obviously your starter has 12 V at the big terminal off the battery and get 12V to solenoid when you turn the key to crank.

You might check to make sure everything is clean and tight at the starter. You might see if you can either jump across the starter terminals, or run a wire from the positive to the small terminal of the starter and see if it cranks. Then check the fusible links by the starter. That solenoid looking thing does not look like a factory part, to me it looks like a Ford starter relay, but we really don't see very many diesels at the shop so if it's left over from then, I could be wrong about that.

Yeah fairly tough online to be able to tell. the big positive cable doesn't go straight to th start it goes to the solenoid thing, and after that it doesn't make it across al the way to the starter.

 

[jfrancom101]

Ok

I think the external soleniods were used as a cheap way to charge dual batteries. You can even buy some that are rated for continuous duty (stock Ford solenoid is not).

My SBC truck has factory dual batteries, and the factory relay for the 2nd battery is pretty light duty. It just connects the charge wire to the battery when the truck is running, but it does not control power to any thing else in the truck/camper.

. It looks like my secondary battery goes to several of the engine part, and to the firrewall ( I assume to the ignition, bit not sure)

 

[WP29P4A]

Does the red wire on the Dist have power when the key is in the run position? Whats your skill level with putting new connectors or terminals on wires? Are you comfortable cutting an old connector off and stripping and crimping a new connector on? Do you have proper tools to do wiring?

I don't want to give you tasks to do that you are not comfortable with, especially if your tool selection for wiring is limited. I'm basically taking inventory to figure how best to help.

 

[WP29P4A]

I have to ask because it's in the picture, what is up with the tiny electric fuel pump? Is it the only fuel pump on the truck? Hard to believe that pump is enough for a V8.

 

[WP29P4A]

Based on what I have seen so far, there is a possibility that you shorted the blue wire that is coiled up, which could have blown a fuse that powers the dist. Need to check fuses to cross that off the list.

I have to drive to the far side of town to trouble shoot camera wiring on a half million dollar motor home right now, I will check back in when I get done.

 

[jfrancom101]

Does the red wire on the Dist have power when the key is in the run position? Whats your skill level with putting new connectors or terminals on wires? Are you comfortable cutting an old connector off and stripping and crimping a new connector on? Do you have proper tools to do wiring?

I don't want to give you tasks to do that you are not comfortable with, especially if your tool selection for wiring is limited. I'm basically taking inventory to figure how best to help.

I've done wiring and crimping and such. Generically with cheap harbor freight kits, and I might have some left over, if not I can always purchase some more.

 

[jfrancom101]

I have to ask because it's in the picture, what is up with the tiny electric fuel pump? Is it the only fuel pump on the truck? Hard to believe that pump is enough for a V8.

Yeah its pretty small. I assumed it must be newer then i'm used to and more efficient. But yeah, I'm used to older alfa romeos and they're just a 4 cylinder and still has a bigger pump.