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Fuel Pump Rewire

This is for you nitrous and turbo users with upgraded fuel pumps. The stock fuel pump wiring uses small gage wire, is very long, and is broken up many times with different connectors. There is a significant voltage drop associated with wiring like this. Once the power finally gets back to the fuel pump, the voltage supplied to the pump can be significantly lower than battery voltage. This isn't that important for a nearly stock car, but people with greater fuel needs can benefit from sending more power to the fuel pump. If you want to get all you can from your upgraded or stock fuel pump, try this mod. Basically, you use the stock fuel pump power wire to turn on a relay which will send power directly from the battery to the fuel pump through heavy gage wire. The power supplied to the fuel pump will be nearly that of the battery.

Here's your grocery list

1. 20 feet of 12, 10, or 8 gage wire
2. Inline fuse holder with heavy gage leads
3. A 30A fuse
4. A simple SPDT relay that can handle as much or more current than the fuse
5. Assorted connectors...wire tap, female spade, stud, butt connectors [don't blame me, I didn't name them]
6. An propane torch can be useful in soldering heavy wire
7. Lots of zip-ties [black if you're as fashion conscious as me]
8. Electrical tape
9. Something to use as a grommet to protect the wire from chaffing on the hole in the firewall
10. You may need an electric drill to make a hole in the firewall
11. A multi-meter is useful if you don't know which wire is which


Here is the first leg of the wire's journey. Please remove the negative battery cable before doing any electrical work like this. The stud connector is bolted to the battery terminal and connected to the inline fuse holder which is connected to the heavy wire. Leave the actual fuse out for now. You can zip-tie the wire to another bundle of wires in the engine bay. You may have to drill a hole in the firewall for the wire to pass through. Make it big enough to accomodate the wire with a grommet around it.


Here is the wire passing through the firewall and down into the driver's side foot well. You can continue to zip-tie to other wires and direct the wire down to the door sill [right name?]


Now pull up the door sill and any other interior peices that the wire has to run under. You can pull back the carpeting some and route the wire in between the chassis and the other wire harness. This should give the wire lots of protection.


Pull the back seat out [there are 2 pull-tabs near the front of the seat]. Keep running the wire under the carpet from the driver's side to the passenger's side. Run the wire up from under the carpet to the stock fuel pump harness. Remove the passenger's side plastic panel with the speaker grill in it. Now all you have to do is hook up the relay.

This is a quick schematic of the connections you have to make. Your relay may be slightly different, so keep that in mind. Use a wire tap to get a ground connection for the relay. The stock fuel pump ground wire for my car was solid black [use a multi-meter if there is some doubt]. You can solder or use spade connectors to connect the stock fuel pump power wire to the relay. For my car, the stock fuel pump wire was black with a blue stripe. If you don't know what wire to cut, you can unscrew the metal fuel pump cover and look at the wires going to the fuel pump. The cover can be seen in the previous picture. Tape everything up thoroughly with electrical tape and zip-tie the whole thing back where the plastic panel with the speaker grill in it was. Put the fuse in the fuse holder and give the system a try before putting everything back together. Remember to put the negative battery cable back on. Just turning the ignition key to the start position should activate the fuel pump for a second. If it works, then take a test drive. If it doesn't work, check all the connections again.

Contributed by Corbin

Cars Modifications Power Turbo Fuel_System Fuel Pump Re-wire

Document statistics: Last modified on 2008-12-14 13:03:54 by Corbin

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