Hey, I was wondering if someone could help me with my fuel pump issues. To give a little history of my current progress, I am almost done with my 818s build in Gaithersburg, MD. The car was running last year but I build progress slowed down to a crawl when I moved to baltimore and did not have a garage to store my car so I kept the car at my parent's house. When I moved it, I was able to drive the car around and into the trailer. Now that I am just about ready to go get it inspected, the car started having problems starting and idling. I found out my fuel pump was stopped working. I have an external fuel gauge so I could verify that there was 0 pressure.

Normally when I turned the car from off to acc, I would hear my fuel pump turn on and prime the system but now it does not do that. I replace my stock fuel pump with an AEM aftermarket fuel pump in case that it was a bad pump because while it was in storage or in case it was just old but that did not help. I checked the voltage at the connector to the fuel pump and it was only producing 10 volts which I am guessing is the problem but I am not 100% sure because I think the fuel pump module may change the duty cycle of the pump from 0%, 33%, 66%, and 100% instead of changing the voltage and it may just be that my multimeter just took an average. To test this, I disconnected the fuel pump module and shorted pins 1-4 and 3-6 so the fuel pump relay (that was providing 12volts) controlled the fuel pump directly. After I did that and turned on the car, I could hear fuel pump turn on and the external fuel pressure gauge showed I had pressure. I was hoping I had a bad fuel pump module so I bought I used one online and replace my old one but unfortunately that did not fix the problem. The only thing left I can think of is if the ECU is not giving the correct signal to the fuel pump module.

Any suggestions on what could be the cause of my problem? not sure if it is a bad ground or something but I would not know which ground to check. Or should I bypass my fuel pump module and just have the fuel pump run constantly when I turn it on ACC?