The bad thing is, more than just one thing got installed at one time, so I can't really tell which part is to blame. Installed the AFPR and cranked up the pressure on a stock pump +20%, made the adjustment on the S-AFC and everything was fine. For some reason I can't get the same fuel pressure (or even stock pressure) on a Walbro fuel pump. I tried 2 pumps thinking first must have been defective and same thing on both of them. Then I trided the pumps off the car in a test environment (two cans, one filled with fuel, timer, walbro pump and a AFPR) and everything worked like a charm, I was able to get the pressure as high as I need. So the problem is clearly in the car, not in the pump.

BTW, the car is a '90, 7M-GTE with just the BPU level mods (MHG, intake, exhaust, boost controller, Apexi S-AFC and AFPR).

The bad thing is, more than just one thing got installed at one time, so I can't really tell which part is to blame. Installed the AFPR and cranked up the pressure on a stock pump +20%, made the adjustment on the S-AFC and everything was fine. For some reason I can't get the same fuel pressure (or even stock pressure) on a Walbro fuel pump. I tried 2 pumps thinking first must have been defective and same thing on both of them. Then I trided the pumps off the car in a test environment (two cans, one filled with fuel, timer, walbro pump and a AFPR) and everything worked like a charm, I was able to get the pressure as high as I need. So the problem is clearly in the car, not in the pump.

BTW, the car is a '90, 7M-GTE with just the BPU level mods (MHG, intake, exhaust, boost controller, Apexi S-AFC and AFPR).

On The passenger side of your engine bay there is a unit controlling the voltage to the pump, have you made sure that you are running 12V to the pump and not the 9V as the stock system does(You will have to shorten 2 wires at the connection).

A Walbro cannot run on 9V so that is a necessary mod to do.

HTH

Whoa, thanks! That must be it, since in the test environment I tested the Walbro pump connected directly to a 12V car battery. Any resource that describes which wires have to be shortened?

Whoa, thanks! That must be it, since in the test environment I tested the Walbro pump connected directly to a 12V car battery. Any resource that describes which wires have to be shortened?

This should help you a bit:

http://www.thesupraforums.com/attachment.php?attachmentid=143&stc=1

Great! Thanks for clearing things up a bit. But won't eliminating the relay make the fuel pump stay ON all the time, while the ignition key is turned to ACC? I thought the relay was there for a reason, to cut power to the pump when it was not needed. Maybe I can keep the relay, but eliminate the resistor, so that the voltage is 12?

Finally got arround to doing the mod. It's proper winter here and freezing cold in the garage. Well, I'm delighted to say, it worked. The fuel pressure is as it should be and I can actually crank it up a notch to push the fuel-cut further away.
Thanks again, supra4ever!

This should help you a bit:

http://www.thesupraforums.com/attachment.php?attachmentid=143&stc=1


here is the 12v fuel mod in it's entirety, for those who are interested. i just figured i'd post how to do the whole thing, rather than just one single part. :) this is how i did it, hope the diagrams help. that one above looks familiar ;) i'm glad to see people making use of my diagrams. it turns out that microsoft paint IS useful after all! haha :drinking:
http://www.supramania.com/forums/showthread.php?t=9417


sorry to bump a dead thread. :(

-shaeff

While on the subject, does anyone have a diagram of how the second Walbro fuel pump should be hooked up? Also, since they?e both electric motors, I'd probably have to use some electromagnetic screening between them, so they don't interfere with each other. What material is best used for this screen?