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Alternative fuel pump rewire

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Here's yet another way to rewire your fuel pump. I like this method because you can just grab a relay from a junked DSM and it'll snap right into your factory setup for a nice clean install. It keeps all your fuses together and it also puts the ground wire under the dash so it is easy to install a hidden fuel pump kill switch within reach of the driver. It's also dirt cheap to do. The only thing I bought was a length of 12ga wire. I already had everything else lying around the garage thanks to a spare toasted wiring harness and some junkyard relays I had.

1. If you pull the knee guard on 1g's (not sure on 2g's) there are a few empty sockets where relays can go. You'll be using one of these as well as an empty fuse holder under the hood.

2. The wiring is basically the same as any fuel pump rewire. Find the black wire with a white stripe on it coming from the fuel pump cover (on my 90 it is the one closest to the back of the car.) Double check that it has +12 volts going to it.

3. Disconnect the battery so you don't fry yourself.

4. Cut the wire on the car side of the plug. LATER you'll attach your new thicker 10-12ga wire to the pump portion of the wire. I used a crimp connector and wrapped it with electrical tape but you really should solder it and shrink wrap it. You can leave the other end of the wire going into the wiring harness loose. You'll be cutting it up by the dash soon. Run the new power line under your driver's side trim up towards the fuse block under the dash. In the photo of the wiring harness, the red wire I drew a green stripe next to is the new power line.

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5. When you pull the door sill pull the carpet back and you'll see part of the wiring harness coming from the back of the car as shown in the photo above. Pull the shrink wrap off of it and dig towards the center. You're looking for that black wire with the white stripe that is pulled out and circled in the photo. Don't cut it yet!

6. I found two wires in the harness that were black and white. There is only one the right size and it should be the thinner one. This is why you left the new power wire loose. Loosely connect the new power wire to the end of the old power wire back by the fuel pump. Now go back to the front of the car and grab your multimeter. Poke one tester through the insulation on the circled black & white wire and attached the other tester to the end of the new power wire you ran up to the dash. Check for continuity. If you get a reading, you have the right wire.

7. Once you've verified you have the right wire.... Cut it, prefferably closer to the rear of the doorway than I did so you can pull more out to reach under the dash (I had to splice in a section to reach.) Now it is safe to go to the back of the car again and permanantly attach the new (red) power wire to the pump side of the harness.

At this point you'll want to start running your other wires.

8. I ran my battery power line through the same rubber grommet we run our boost gauge vac line through on the driver's side firewall next to the steering column. You'll have to cut or drill it to get the wire through, as it is tight.

9. Run the wire along the firewall of the engine bay and over to the passenger side fuse block. I went back and tucked mine into the zip ties the factory harness runs through so it is secure and hidden. There should be three empty slots in it as shown in the picture below, though mine already has my fuse installed and circled. Unbolt the fuse block and unplug the harness from it so you can get to both sides easily. Push your wire up through the base of one side of the empty fuse you'll be using, doesn't matter which side. In my pile of wire ends I had a few push-on fittings that fit the base of the sandard fuses we use. Crimp or solder one of these on and push the fitting down into the fuse block. Do the same thing with another 16" section of 10-12ga wire on the other half of the fuse socket. This will eventually run to the positive terminal of the battery. Check to see if your fuse fits snugly.

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10. Now you'll need the right ends to fit into the relay socket. Standard blue crimp ends should fit but I was cheap and dug through my spare harness to come up with a few plugs that had the right size connections with heavy gauge wire already attached. I yanked a few of these and wired them in with the lines I already had run. Follow the picture below to attach everything to the right locations.


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11. At this point you'll want to find a location for your kill switch and ground. Put it wherever you want, just be sure you have a good ground with no paint blocking the contact. This wire doesn't have to be very heavy since all it is doing is grounding the relay, not the pump itself.

12. Once you have all the wires running to the right spots, install your 30 amp fuse and relay. Hook the battery back up and see if your fuel pump works! Now turn off your kill switch and see if it doesn't! Isn't that nice. Now you can put your trim panels back in and enjoy the fact that your fuel pump no longer changes pitch when your turn signal blinks.

Any questions, comments, corrections or suggestions? Please PM me!
 
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