Was driving home a little bit ago, and the truck felt off, so I hooked the scan tool up. Fuel system was in open loop fault the whole way. O2 sensors read at most .02 or lower. LTFT stayed at 0 which is out of character for my truck. Normally they're pegged at +25. lol. STFT was at around +10 like normal. B1S1 O2 sensor is new and switching well. B1S2 needs replaced, but seemed to be switching well in open loop fault. New plugs, wires, coil, fuel pump, fuel filter, fuel pressure regulator, air filter, and intake manifold gasket within the last few months. Everything else on the scan tool appeared normal. There is a TSB out on the MAF sensor, but the readout looks normal on it. TPS looks normal too. Fuel pressure is low, hence the lean codes and fuel trims. It's about 35 on the rear pump and the front pump goes anywhere from 15 to 45 PSI. I shut the truck off and restarted it, and it was still in open loop fault. Any ideas?

 

She started out in OL fault again this morning, but went quickly into CL. On the rear pump everything is normal now, but if I switch to the front pump, the O2 sensors bottom out in voltage, reading extremely rich. The computer responds by raising the STFT to somewhere between +25 to +32. Switch back to the rear tank, and everything is back to normal. With it feeding more fuel into an already very rich mixture, it leads me to think the computer is bad, but if it's only on the front pump, maybe the fuel pump power and the O2 sensors are grounding to each other?