2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Fuel pump rewire

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Old Jun 23, 2009 | 10:31 AM
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gear_grinder's Avatar
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Fuel pump rewire

hi, i have a 87 TII.

i want to rewire my fuel pump because i do. i have a AFPR but run stock ecu w/ rtek 1.8, could i rewire it the OVERKILL way just without overkill wires?

thanks.
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Old Jun 23, 2009 | 11:17 AM
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What's the "overkill way"? The most useful part of the fuel pump rewire is removing the fuel pump resistor/relay. A lot of times the stock wires themselves can still be in decent shape, but every case is different.
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Old Jun 23, 2009 | 12:15 PM
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The "overkill" way was when I bypassed the resistor relay and ran straight 8 gauge into the fuel tank for a Supra pump. There were no factory wires reused at all. Most other rewire jobs splice into at least some factory wiring and use 10 or 12 gauge wire. I ran 21psi on a T04S turbo with this setup, no issues, no dual pump setup or Boost-a-Pump style amplifier needed.

But if you have an Rtek 1.8 you are not going to be making enough power to do that. Who is to say that what I did was even "necessary" ? And I had a Power FC in addition to an aftermarket FPR, so I could easily retune the idle. But i bet if you set your FPR to a base pressure near stock (36psi without a vacuum source?) removing the fuel pump resistor wouldn't affect the idle mixture too much.

What I'm trying to say is, don't do what I did. It really is "overkill" for your setup, although it may not have been for mine.
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Old Jun 23, 2009 | 06:02 PM
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Check the voltage at the fuel pump, if its lower than source (13.5+), rewire the pump.
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Old Jun 24, 2009 | 10:15 AM
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well, when i was setting my AFPR i could only get it to 30psi max. with it all the way closed off. but i did have a vacume source (dough!) so i'll have to check it again w/o and see if the presure gets up to my desired 35-40psi

PS i have walbro 255
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Old Jun 25, 2009 | 10:35 PM
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checked it with the car not running, but everything but the lights, whipers, and igniton on. (i have no radio, and i also have an e-fan along with the aux fan running all the time.) pushed the afm flapper open by hand and the fuelpressure instantly shot up to 40psi.
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Old Jun 25, 2009 | 11:16 PM
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I usually set my fuel pressure with the engine off, key in the on position, and fuel pump diagnostic connector jumpered. The diagnostic connector is a yellow two prong connector on the passenger strut tower.
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