why everyone should rewire their fuel pump
#1
why everyone should rewire their fuel pump
How many of you have put a volt meter on the fuel pump on a dyno? I saw something scary this past week. Car I was having tuned had 550s/1680s, aeromotive fpr, supra tt pump, new oem fuel filter. Should have been enough fuel for close to 500 rwhp.around 16 psi boost we hit 100% injector duty cycle. Base fuel pressure was 40 psi.Car should have had injector to spare. I watched the fuel pressure gauge and under boost it shot to 60 psi and by 5000 rpm started falling. Fuel pressure fell as low as 40 psi.This explained why we had to add so much fuel at the top of the map. Next I put a volt meter on the fuel pump and was shocked to see just over 11v! Made no differnce if it was at idle ore wot. Car has a new alternator and odyssey 925 battery. Voltage on datalogit was over 12v at all times. This shows how much voltage drop there is in the junk factory wiring, As these cars age and are tampered with it gets worse.The fuel pump should have over 13v. This is another reason motors blow.
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Tristan Morales (03-06-19)
#11
It's finally reliable
iTrader: (18)
ok so.from battery run 10g wire with 20v fuse in between to #30 on the relay.Then cut the stock supply line to the fuel pump and run 10g wire from #87 relay to stock wire pump side.then run 10g wire from #86 relay to the car side of the stock supply line. is this correct?
and this bosh relay can be found by the fuel pump under the fuel pump cover is this correct?
and this bosh relay can be found by the fuel pump under the fuel pump cover is this correct?
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gracer7-rx7 (12-04-19)
#14
The other nice thing about rewiring the pump is that say you are using the standard wiring system, and the car is running/tuned well. If the speed relay or the ecu driver for the speed relay fails you will have no way of knowing. The pressure will fall, you could lean out and boom.
#18
wannaspeed.com
iTrader: (23)
it doesn't have to be a bosch relay any 4 or 5 prong relay will work. Just make sure the red/wht wire goes to one of the coil side's of the relay, and ground goes to the other. This will make sure the relay is activated the same as the stock fuel pump is. Then the switched portion of the wire goes between the battery 12v+ and fuel pump. It's really simple.
If you want to go all out you can run a new wire off the pump and connect it to the relay instead of using the other side of the red/wht wire that was cut. Here's how I ran my wire.
If you want to go all out you can run a new wire off the pump and connect it to the relay instead of using the other side of the red/wht wire that was cut. Here's how I ran my wire.
#19
Lives on the Forum
iTrader: (8)
I have also rewired my fuel pump the way Dudemaaanownsanrx7 has shown. Fixed all my fuel problems I was having before. Dudemaaanownsanrx7, how did you seal those power lines going intank? I just used a rubber grommet like the one you have and used a bunch of slow drying epoxy.
thewird
thewird
#20
Polishing Fiend
iTrader: (139)
I have also rewired my fuel pump the way Dudemaaanownsanrx7 has shown. Fixed all my fuel problems I was having before. Dudemaaanownsanrx7, how did you seal those power lines going intank? I just used a rubber grommet like the one you have and used a bunch of slow drying epoxy.
thewird
thewird
Crispy