I'm trying to trouble shoot a problem in one of my e30's and I am wondering if the fuel pump is supposed to be pumping while the motor is turning over (on startup) or if it just primes the fuel system when the key is in the "on" position and then starts working when the motor is running.
When I put a test light on the fuel pump it gets power when the key is in the "on" position and then the relay shuts it off after a few seconds. But the test light goes off when I am actually trying to start the car. Once the car starts the test light is on again and obviously the fuel pump is working.
Sometimes my car starts up poorly but it starts almost everytime. I think the fuel pump should be pumping while the motor is trying to start but before I rip apart the wiring harness I wanted to know if that is supposed to happen or if the motor just starts from the primed fuel pumped into the lines when the key is in the on position. If my wording is bad then I can re-word it, just let me know.
Thanks for the advice