Mechanics

DODGE TRUCK FUEL PUMP PROBLEM

1994 Dodge Truck • 200,000 miles

I have a 1994 dodge ram 1500 2wd with the 318 (5.2) in it I'm having problem with it not starting I thought it was the fuel pump because I wasn't hearing it come on but when I change the fuel pump motor out still would come on so I traced the wires and found some burnt out wires where the fuel pump runs in with the tail light wires I believe it had a bad ground but I'm not sure I have them all wired back together but this one black wire coming off the fuel pump I think it's a ground but I'm not sure I'm not good with electrical stuff if any one has a fuel pump wiring diagram that would be helpful
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Tlorraine0001
February 22, 2013.



I can't read that huge sentence properly with no punctuation. You said you "changed the motor and it still comes on". So is it running or isn't it? Are you aware the pump should only run for one second after turning on the ignition switch, then again during engine cranking? Do you have the manufacturer's service manual? If not, I can try to find one. "Burned out wires" can mean a lot of different things. What else doesn't work?

Caradiodoc
Feb 22, 2013.
Sorry I typed would instead of wouldnt. I changed the motor in the pump becuase I thought that was the problem but its not the pump is still not getting power. I then found the wires were melted and a couple of them were melted in two. I have all the wires that were melted, spliced back together and covered with heat shrink tubes except the the black wire coming from the fuel pump. There is four wires coming from the fuel pump plug a blue one, a black and white one, a green and black one, and a solid black one. The solid back is the one that I don't know we're it needs to go. Also yes I know that the fuel pump only comes on for one second.

Tiny
Tlorraine0001
Feb 22, 2013.
Dandy.

Black / white and dark blue are for the fuel gauge sending unit.

Dark green / black is the 12 volt feed to the pump.

Black is the ground wire for the pump. It is spliced in with the ground wires for the tail lights, license lights and backup lights, but they neglected to show where that ground attaches to the body. If all the rear lights work, you can safely attach that black wire to the body. If any of the rear lights don't work or if they work incorrectly, I'll try to figure out where that splice is located. That, and the ground connection, would be the two logical places to find a problem.

Caradiodoc
Feb 22, 2013.
Ok thats what I did I spliced the solid black wire in with the black wire running back to the tail lights but still no power. I currently have the bed off my truck and the tail lights unhooked would that affect it.

Tiny
Tlorraine0001
Feb 22, 2013.
I can't determine where the ground wire is bolted to. I suspect it goes to the frame because the box is on rubber isolators, but then again, the lights normally ground to the box, ... So there would have to be a ground strap somewhere.

The fastest for now is to determine which you're missing, 12 volts, ground, or both. Use an ohm meter to measure the resistance to the frame on that ground wire. It should be real low, as in a couple of ohms. If you have that, test for 12 volts on the dark green / black wire. A lot of digital meters don't respond fast enough to catch that during the first second so a test light might be more accurate.

Caradiodoc
Feb 22, 2013.
Ok I will work on getting a ohm meter and a light tester because I don't have them. I'm not real good with all this electrical stuff. But I hooked up the tail lights and there not working along with the fuel pump is still not kicking on so that would mean I got a ground off some we're right.

Tiny
Tlorraine0001
Feb 22, 2013.