Hey all, I have a new Spectra rear fuel tank with a new Delphi fuel pump. I'm getting P0171 & P0174 codes and the truck seems to be lacking power consistent with not enough fuel pressure.
What should I do first? I've got a new distributor, plugs, plug wires, ICM, ignition coil, air filter & fuel filter. A local shop fixed 3 bad ground connections a few months ago.
Also, what brand of fuel pump do you recommend, in case my new Delphi isn't making enough pressure? Thanks in advance.

phoskins
1996 F150 4.9 4x4 XLT M5OD

 

Rent a fuel pressure tester and if it's below spec, then warranty the pump.

The 300 needs minimum of 45psi. If the pump isn't able to build and hold that, then I would say the pump is bad.