selfproclaimedv8buff

i was just wondering how i should go about checking to see if the ecu is sending a signal to the fuel pump to turn on. I found the car won't start, its not getting fuel at the engine, fuel pump works(manually), won't turn on with key turned in ignition. how do i go about checking the signal to the pump? I'm guessing i should probably tap into the 3rd pin (the one responsible for the fuel pump relay on the ecu) but tap into the harness while the ecu is plugged in and see if i'm getting current through that wire. sounds legit to me! any experience out there that can back me up or give me better advice?

I wonder if for a temporary time i could hard wire the fuel pump and have a toggle switch to turn it on whenever i'm driving the car and off when i'm not. i wonder if the ecu would appreciate that. i believe thats exactly what i was doing to my ol' 10vt when i had to hardwire the fuel pump so it wouldn't cut off at 15psi. hmmm ... any suggestions?

CARSNPLANES

Unless I'm mistaken, I don't think the fuel pump will just turn on with the key turned to ignition. The residual pressure and the coldstart valve will start the car and once it's started, the ecu knows this and continues with turning the fuel pump on continous. If the engine stalls, the fuel pump will stop. It's a safety so the pump won't continue to operate in case of an accident and cause a fire.
I had a '86 Coupe GT with KZ engine (non ECU) and that had to see oil pressure for the fuel pump to operate. I'm not sure on my 87 5000tq when the ecu finally gives the signal to the fuel pump to operate. I just know it's not just when the key is turned. If you have the fuel pump relay with slots on top for a fuse, you can check fuel pump operation that way. (insert a fuse, then turn on the key to ign, the pump will operate as long as the fuse is in a ign on). Do not leave it in that way , it will flood the engine. i'ts only to test the pump operation.
For your situation, testing the pump that way is the first step to ensure the pump relay is working and the pump itself is working. Check CIS fuses? If relay and pump are good then you'll have to look elsewhere. If you suspect ecu, try removing and installing the plug on the ecu. There have been instances where water can collect near the ecu mounting and connector and cuase corrosion. It should be protected with a plastic bag on connector(stock audi bag). Rarely it's the ecu itself.
Good luck

selfproclaimedv8buff

i went ahead and checked my CIS fuses beforehand. from what i saw it was actually only one fuse, which was #13. i then proceeded to check ALL my fuses and they're all fine. It will be a great idea to try to actually insert a fuse in the fuel pump relay and see when i turn the ignition what happens. another thing is that i've actually cranked the car without it starting so when i'm cranking the car should start the fuel pump. after cranking for maybe 10 seconds i get a oil pressure warning light so i stop. any other ideas?

boxerfan

CSV and residual pressure start the car then the FP kicks in. I'm not sure if this is correct but it may be.

If you use the test fuse location your pump will be forced to start right away so pressure loss issues will be mitigated.... I think.

Good luck.