3000GT/Stealth Fuel Pump Hot Wire

by Bryan Rogers
(Web page design and editing by Jeff Lucius)


[Editor's Note: The stock fuel pump wiring consists mostly of 16-gauge wire that is routed through the engine control relay and a resistor. This wiring path to the pump may result in less than full alternator output voltage reaching the pump (especially during high-load, wide-open-throttle use) and consequently fuel pump flow may be less than optimal. The "hot wire" mod supplies full alternator/battery voltage to the pump using a relay, which is a heavy-duty switch that supplies high current, yet is switched by a substantially smaller current. The relay will have 4 or 5 connectors on it: one for a fused wired directly from the battery, one for a wire to ground, one for a wire from the low-voltage switch (the stock pump power wire from the harness in this case), one for a wire to the normally open device (the stock pump power wire on the pump electrical connector), and maybe one for a wire to the normally closed device (not used in this case). The fused wire directly from the battery to the relay should be 8 to 10 gauge or less to minimize resistance along the wire and maximize voltage supply to the pump. You can expect high-draw Denso fuel pumps, such as the "Supra" pump, to draw a little over 20 amps with a 14 volt supply at fuel line pressures greater than 70 psi (over 27 psi boost). So a 30-amp relay should be used. You can start with 20-amp fuses, and increase the fuses to 30-amp ones if necessary.]

1. This picture shows what you need:
     - 30 Amp Relay
     - about 15ft of 10 ga. wire
     - fuse holder
     - 20 amp fuses for the fuse holder
     - soldering iron
     - solder
     - electrical tape		 Fuel pump hot wire pic 1
2. This shows the fuse holder with an eye connector soldered on. The side with the eye bolts right on to your battery terminal. Fuel pump hot wire pic 2
3. This shows the side that is going to the battery all sealed up with heat shrink tubing. You can use electrical tape also. I just think heat shrink tubing looks cleaner. Fuel pump hot wire pic 3
4. This shows the fuse holder connected to the battery and also crimped onto the 10ga. wire. I had a 100-ft roll of 10ga. laying around and so my wire changes from black to white because I decided to use the continous strand rather than crimping 5-ft pieces together. Fuel pump hot wire pic 4
5. This shows the wire loom zip tied to the existing brake lines that run along the firewall. You probably won't be able to get them under the brake lines like I did because you probably won't have the turbos out when you do the install. Anywhere back there is fine. Be sure to loom all wires you run in the engine bay to keep them from getting to hot. Fuel pump hot wire pic 5
6. This shows the hole in the firewall where I ran the wire through. If you havn't run any other wires just get a drill and drill a small hole through this area to allow the wire through. Fuel pump hot wire pic 6
7. This is a picture of the door sill trim removed. You have to remove this to run the wire along under the carpet without too much hassle. Fuel pump hot wire pic 7
8. This picture shows the other trim piece removed that surrounds the trunk pop and fuel door levers. Fuel pump hot wire pic 8
9. This is a picture of the trim piece in the previous step. Fuel pump hot wire pic 9
10. Here you can see the carpet pulled back giving you plenty of room to run the wire down underneath it where noone will ever see it again! Fuel pump hot wire pic 10
11. This shows the back seat bottom removed (it's really easy, just pull the tabs under the seat and pull up) and the wire run accros the door and waiting to go under the side trim panel. Fuel pump hot wire pic 11
12. This shows the coat hanger used to fish the wire under the trim panel pushed through to grab the wire. Just tape the wire to the coat hanger and pull. Fuel pump hot wire pic 12
13. Voila! The wire is run under the panel. Fuel pump hot wire pic 13
14. Tuck the wire underneath the seat back and run it under the trim as much as possible. I taped it to the floor here where it has no trim to hide under. Fuel pump hot wire pic 14
15. This shows the carpet put back, and look the wire is almost hidden. Fuel pump hot wire pic 15
16. The wire is run to the panel on the passenger side and then underneath the panel. It is run over the hump and into the trunk. Fuel pump hot wire pic 16
17. Now run it under the trim pieces so it won't show and then right over to the cover to the fuel pump assembly. Fuel pump hot wire pic 17
18. Take the blue thing out and unhook the stock wiring harness. This gives you more room to work as you are crouched in the trunk of your car. Fuel pump hot wire pic 18
19. This shows the stock power wire to the pump (look how small and dinky it is!). Just cut this wire and put the wire connectors on it so it will just slide right onto the relay before you soldered them on.

Stock wiring assignments:
   Black w/ red stripe: Ground
   Black: Ground on pump assembly frame
   Black w/ blue stripe: Power
   Yellow: Fuel gauge
   Yellow w/ blue stripe: Low fuel warning 		Fuel pump hot wire pic 19
20. This wire I made to ground the new relay to. Fuel pump hot wire pic 20
21. This shows all the wires soldered onto the relay. Fuel pump hot wire pic 21
22. All put back together and you can hardly see anything. That tray will cover it right up! Fuel pump hot wire pic 22
23. Seat and door trim all back in and you can't see anything. Noone will know! Fuel pump hot wire pic 23


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Except for the small gif and jpg images, the content, images, photographs, text, and multimedia displayed are Copyright ©2000-2002 by Bryan Rogers, Jeff Lucius, and K2 Software. All rights reserved. No part, section, image, photo, article, or whole of this site may be reposted or redisplayed without permission of the author.
Page last updated March 17, 2002.