Hello,

I have an '85 EFI 5.0 dual tank F250 and was doing some testing to confirm that my in-tank pumps were working properly after running all new wires and connectors to them. I'll attach the pinout I used. The pumps themselves are only a couple years old. After verifying that I have power at the connectors I connected the harness to the fuel pumps and get what sounds like...nothing. I do get a reading from the fuel tank senders, but I swear I can't hear a thing from the pumps. The high pressure pump on the frame works fine, and it appears to have primed just fine (installed all new fuel lines as well, so started with a bone-dry system). I have 40 PSI at the fuel rail with the engine off. One thing I have not done yet was to disconnect the line to the inlet of the high pressure pump and run it. I was doing this late last Saturday night and wasn't prepared to make a huge gasoline mess everywhere. But until I can get back to it, I can't help but wonder...those low pressure 'lift' pumps are pretty tiny. Can they be running, but just so quiet that I'm not hearing it?

Thank you for your input,

Rick

 

I have noticed new and newer pumps are very quiet. It seems as they get older they get louder.