I'm unclear whether your Dakota can be made to run. You stated that it blows fuses and as soon as the gas line is out of fuel, it stops. Please break that down a little more for me.
Can you get the fuel pump running by cranking the engine?
Does your CHECK ENGINE lamp do a bulb test when they key is turned on? It's designed to do a 2-3 second burn, then shut off at key-on.
Which fuse is the one that blows? If it's underhood, the power distribution center (PDC) will have identification of the circuits by number. If it's under the dash, get me the fuse number (unless you know what circuit it affects). Also let me know what you have to do to cause the fuse to fail.
The relay... Do you feel it's always on? Or is this something that comes on with the key or during cranking?
We'll stop there for now. I do have to work today, but I can check for responses from time to time from you. Get back to me when you can. My name is Ed.
Thanks, Forrest. You pretty much answered the part about the CHECK ENGINE lamp by telling me the engine will run if fuel is poured into the throttle body. That tells me the PCM is awake and producing spark.
While you're out there, you may be able to pull some codes from the engine controller. You use the same CHECK ENGINE lamp to extract flash codes. If your battery is low, get the codes first, so they won't be lost later.
To put the powertrain control module (engine controller/PCM) into diagnostic mode, you turn the ignition key from off to on three times or more within five seconds. Leave the key in the on position to get the flash codes.
The light will burn a bit longer than you're used to seeing once you enter diagnostic mode. At the completion of the burn, the light will go out and pause for several seconds. Blinking starts after that.
All codes it dispenses will be binary, having two digits. The first set of flashes will indicate the first number. A short pause separates the two digits, then the second one is flashed.
At the completion of that code, you will have a longer pause before the next set is flashed. It goes on like this until you read code 55, which means end-of-test. You should always get 55 if the system is working properly. Repeat the test as many times as it takes for you to become familiar with the drill... you'll catch on fast. Let me know what codes you see.
Now, the fuse. I have wiring schematics available to me today, but I probably couldn't determine which fuse it is without a name (number/ circuit ID) from the fuse cover index.
Having your fuel pump hard-wired sure indicates to me that there have been issues in the past with that cirucuit. Sounds like you bought it that way. But you're still having problems getting the fuel pump running? If you can (I know, this is getting long), let me know what's been modified and what manner it was done in.
Back to work now. We'll talk later. Ed
We're getting closer. The ASD relay is energized as soon as the key is turned on for about a second. There was no dedicated fuel pump relay or circuit in 1992 for 2.5 engine Dakota only. The ASD output was shared with fuel pump, injector (just one), ignition coil, oxygen sensor and PCM (allowed PCM to set a code, should no ASD output be present).
Your short could be anywhere among these locations, but it sounds like you have something going with the fuel pump. If you can disconnect the fuel pump and not blow a fuse, it looks like you have it localized. The add-on wiring concerns me, though. If there is any way to remove the overlay harness and go back to the factory system, I would sure recommend that. The fuel system must stop pumping in the event of an accident, and I'm not sure that's a possibility the way it sits now.
Should it turn out that the fuel pump or its circuit isn't at fault, go around a unplug each of the above listed items one at a time. If it still blows the fuse, you're going to be looking for a harness short somewhere. Pay particular attention to areas where the harness may bend around metal objects (cylinder head rear) or touch sharp metal edges (valve cover, mounting studs, etc).
There's a handy tool sold by Harbor Freight (among others) that consists of a circuit breaker (20a) and a magnetic detector gauge. If you have a short, connect the breaker into the circuit. It will immediately open the circuit, but will in the process create an electromagnetic pulse that the detector (looks like a compass) can pick up. You scan the detector over the harness, waiting for the breaker to reset/break. Each time it does, the pulse can be picked up as you move along, until you pass the short. Then the pulse weakens considerably or disappears completely. I don't know what I'd do without mine. I've worn out several over the years. It comes with better instructions than this, so don't worry. Good stuff.
I believe you're well on your way, Forrest. Stick with it and you'll be at the end of the road in no time. Thank your friend for me, too. I'm going to cut you loose for now, but I'll still be here, should you need additional help. That's what I'm here for. Take care, Ed.