07 dgc sxt 3.8 138,000 won't run. New fuel pump 3 months ago, code p0171 a week ago and started getting hard to start, replaced o2 sensor and cleared code - cranks, hits, but won't run, replaced plugs and wires (old ones were factory and very very bad)- no change, replaced map sensor- no change. Will run with ether but won't stay running.

 

Did you install a new fuel filter when you replaced the pump (I can’t recall if these have an inline filter or not)?

Remove the fuel pump relay and jumper pins 30 & 87 - this bypasses the relay and PCM control and provides direct battery voltage to the fuel pump. If it stays running with this set up, either the relay is bad (easily tested by swapping it with another relay) or the PCM is shutting off the fuel pump. You’ll have to check signals the PCM needs, such as crank and cam sensors.

If it doesn’t stay running, and the fuel pump is new, it could be a power or ground supply problem at the fuel pump. You’d have to disconnect the pump and check for power and ground. You could shortcut this by performing a current draw test at the fuel pump relay - more than about 15 amps indicates high resistance in the circuit.

 

UPDATE: even though the fuel pump was only 3 months old apparently the regulator went south. I replaced the whole assembly and she's running like a new van.