Hi I have an 01 monte ss, I have a voltage drop at the pump of 1-1.5 volts. I put a new pump and included wire harness with plug in, but still same problem. The car runs just not well. When you get on it the fuel pressure drops I am guessing because of the voltage drop, I have replaced a lot of sensors, and the cat. Anyone have any ideas on where to look for where I might be losing voltage. I have good readings under the hood, just drops by the time it gets to the plug on the pump.

 

The length and gauge of the wiring will create some resistance so you will see a slightly lower reading at the pump. A 1 - 1.5 drop would be considered normal. If the car is falling on it's face I'd check for a clogged fuel filter, the output of the fuel pressure regulator, and clogged injectors.

A vacuum leak could also create this scenario, but you should hear a sucking and/or whistling sound under hood.

 

I have put 2 new fuel filters on in the last 2 weeks, strained the gas that was in them thru a strainer and both were clean couldn't get a speck to come out of them. The fuel pressure at the regulator is 55 at an idle, when you hit the gas it drops instantly to 14 psi. I put a new regulator, mass air flow, checked the egr, changed both O2 sensors put a new cat on. I just put another new fuel pump in thinking I got a bad one, still the same. Checked for vacuum leaks and couldn't find any. Could it be a bad computer? I have dumped a lot of money in this car and still no changes. Thanks for the help.