BBB

I just replaced my stock fuel pump with a Wahlbro/Racetronix 255 pump (high pressure). I have been running rich and losing power. Last week I dyno tested the car and the car had a close to ideal A/F ratio of 13.4:1 UNTIL it went to WOT and then it dropped to a rich 11.5:1.

1. Can the high pressure pump cause a surge that would overwhelm the stock pressure regulator?

2. Can I correct the A/F surge with an adjustable regulator?

3. Is there a way to tune this A/F change out? I want the fuel mileage and hp back.



BBB

RamAir95TA

If you're running the stock regulator, and it is functioning properly, you shouldn't need to replace it. I have a Racetronix pump/harness, and I'm running right where I need to be, stock pressure. An AFPR wouldn't help, because the PCM will see the rich condition at part throttle, and add injector pulsewidth to compensate to reach the set air/fuel ratio.

Pull off the vacuum line on your fuel pressure regulator, and see if fuel comes out of it. If so, the rubber diaphram in the regulator is torn, resulting in inconsistent fuel pressure and a rich condition (since fuel is being led back into the intake manifold via the vacuum line).

BBB

Ok, that is an interesting statement. That lead me to this comment. After the car is warmed up an I come back to idle (like at a stop light) the car starts to backfire. If the condition exists like you say could that explain the backfires too?

My car has almost 125.000 miles on it, does the regulator have a certain lifespan to it? I have never really heard much talk about regulator problems.

BBB