I have a Walbro 255 sitting in my room and i haven't finished all the mods i wanted to get done, mostly i just have the intake and exhaust on, haven't put a boost controller on. Would putting that new fuel pump in, effect my car now or will it still supply the same amount of fuel it currently does.

Wasn't sure if it has the potential to supply more fuel when needed, or if it automatically will supply more fuel.

 

You'll run pig rich. Install it right before you plan on getting your tune.

 

you can put it in, the car is gonna run rich but not THAT rich.

 

It won't be that bad. Just like Steve said.

 

how much can u turn it up to wit a fuel pump on 93

 

By it you mean boost? With an VIII, I'd keep it in the 21-22 PSI range tuned. That fuel pump really helps power up top with the VIIIs.

 

This is a question I always wondered about.

Why would it go rich if you are running the same fuel pressure?

I know the Walbro will flow more at the same pressures.... but does that increase in flow translate to flow through the injectors?

 

when you say 22-23psi is that holding till redline???or is that spiking it...???

 

bump to the above question. i would love to know the answer.

 

The answer is the flow at higher pressures.

The fuel pressure regulator should be increasing the fuel pressure from like 40psi as a base and adding 1psi for every psi of boost. Since the stock fuel pump starts to complain around 20psi its no surprise that a better flowing pump at higher pressure suddenly increases flow through the injectors.

I experienced a 1 AFR point drop when i did mine but i was running 22psi of boost at the time. I don't have a fuel pressure gauge to monitor but I'm willing to bet the line pressure with a stock pump is lower than with the walbro when boosting.