Electrical signal not reaching fuel pump

[pwpanas]

Originally Posted by A.BuckShort

RE: My 1993 Supra GTE (nonturbo) with approx. 160,000 miles. Owned since 1996.

Something is preventing the electrical signal from reaching my gas tank fuel pump, causing car to stall, every time, almost immediately after ignition. Test light at fuel pump starts to dim and goes out as pump slows and stops within about 2 minutes. Any thoughts?

Have already drained and cleaned out old gas residue, added gas treatment, manually cleaned throttle, installed new fuel pump and ECU relay. This seemed to solve original problem of not taking the gas and generally requiring starter fluid through the air filter to start after sitting overnight. Now starts without the starter fluid, but then began similar stalling when stopped at a traffic light or slowing for turns. Now above problem with losing electrical to fuel pump and test light, which may have been the real problem to begin with? Now starts without the fluid, but stalls quickly thereafter. Could it relate to however much the engine heats up after ignition?

I had seen some evidence of some kind of likely rodent infestation when initially opening the air filter to spray the starter fluid. Only thing we can think of right now is some animal might have chewed through wire going to the fuel pump somewhere– but uncertain how to look for that or if should be looking for something else?

Minor point but GTE means turbo. GE is non-turbo.

I don't know the GE that well, but hopefully it's got enough in common with the GTE for me to help. On the GTE, there's an ecu that controls the fuel pump. It's function is to run the fuel pump at 9v off boost, and then switch to 12v when boosting. It's located on the inside of the left rear fender, behind the tire, and below (not behind) the plastic trim panel that covers up to the hatch. The GE might have something similar, just to help with fuel economy...so that'd be my first guess - that your fuel pump ECU has gone bad. If you know someone else with a GE, you could try to swap it?

If that's not it, or you want to try something else, just add a new fused circuit from your fuse box, and run a new wire back directly to your fuel pump. Ideally, you'd trigger this with a relay from an existing ignition-switched circuit. This would run your fuel pump at 12v continuously whenever your key is on, bypassing the fuel pump ecu. If this fixes the problem, it'd definitely isolate the issue to your fuel pump ecu or the fuel pump wiring.

Another thing to do would be to put your test light onto the 12v input line into your fuel pump ecu (again, assuming the GE has such a thing). If that line doesn't flicker, you eliminate a possible any wiring issue before that point. If you also test right at the fuel pump ecu's output next, and it does flicker, you've nailed the problem down to the fuel pump ecu for sure.

Hopefully some of that helps. If not, please ask more questions!