2000 Taurus - loss of fuel pressure, surging when A/C is on

[thdarkknight]

I currently have a 2000 taurus in the shop at this time below are the following symptoms.

after extended driving fuel pressure gradually drops to 0 then after the car sits for a moment then the car will re-start and run ok for a bit then it will drop again. cold start if runs fine with 40psi. havent been to the point to test voltage yet until it falls on its face again.

secondly, the car will surge at all throttle positions when the a/c is on. will go from 690rpm to 1100 rpm then at 2000 rpm will go up the 2400 rpm at a steady pedal.

there is a new syncronizer, mass air flow sensor, plugs and wires, fuel filter, reman transmission also, these conditions where evident prior to replacement of transmission.

according to our solus scanner when running graphs there is nothing individually sticking out point us in a direction for a repair.

Thanks
Sal

[shorod]

Those symptoms are quite consistent with a failing electric fuel pump. Have you noticed any change in symptoms when the tank is full of fuel versus low? If the symptoms are worse on a low tank, I'd just about put money on the fuel pump as the cause.

-Rod

[thdarkknight]

with running the data stream on the car during a test drive the pressure at the rail tanked a few times but when i scrolled through the data the fuel pressure at the tank soared up to 75psi while at the rail it read 9psi. this is what has got me perplexed on this. this was discovered since my last post. would a fuel pressure regulator allow the pressure to drop like that???

[shorod]

The tank pressure is separate from the fuel rail pressure and unrelated to the fuel pump. The tank pressure is related to the EVAP system. It sounds like you have a weak fuel pump, or you managed to install the fuel filter in reverse.

-Rod