What powers the fuel pump on 1990 BMW 325i? on 1990 BMW 325i

The main and fuel pump relays were replaced. Testing the fuel pump shows that it works, but in the car will not operate. Any suggestions what to do from here?

Asked by for the 1990 BMW 325i
whta is the actual fuel pressure?
That I don't have. Dont have the tool for testing. Will a garage test it for free? Spending money fast on parts already. Or can you test the pressure without the pump being on?
ck with a local shop on cost