4g61t.org

I've been told that a 255 will "blow out" a stock FPR, and I'm wondering if there's an validity to that statement. I might just go with an Aeromotive unit for the hell of it, but I want to know if I'll be able to run for a while before having to drop the $$ on it.

BTW, I ran a 255 on my 240 (w/SR20 and stock fpr) for about a year with no issues. But I have seen a DSM fpr crap out.

I've heard of people running it with a stock fpr but imo it's a better idea to run an afpr right off the bat, no need to worry about anything.

Highly recommended to have an AFPR. You'll be chasing your tail trying to get an excellent tune.

You don't need it, but it's really not a bad idea to get one. The biggest thing the Walbro will affect is idle, you'll be up around 55psi on the stock regulator, and once you factor in boost it only goes up from there--this puts a lot more stress on the pump and causes it to flow less, and the high pressure doesn't make your injectors happy either.

Yes, a 255 Walbro will walk all over your stock FPR - guaranteed. Anyone who says different is uninformed. You will run pig rich, maybe have some rich misfires, and constantly be re-tuning since your FPR will never rise 1:1. IMO there is no sense in upgrading your fuel pump without first having the means to dial down the pressure.

You really don't need one i dynoed 503hp uncorrected on 1000's and a hp 255 wally on e-85 with the stock fpr...Bobby ran tens in his mirage with a 255 wally and stock fpr...I also daily drive my car with no idle issues but what do i know im ill informed....

Who cares what you dynoed or who ran what at the track...?
The original poster wanted to know if a Wally 255 would overrun a stock FPR and the long and short answer is yes. Just because you haven't figured it out yet doesn't mean it ain't so.

Scroll to post #25: http://www.dsmtuners.com/forums/newbie- ... k-fpr.html

My stock 4g63t regulator keeps pressure right around 40-42 psi at idle with a 255 intank(no rewire), but I do run rich. I have an AFPR just haven't put it on. I would recommend it like most people have.

Interesting. My car ran at like 55psi with a 255HP on the stock regulator. It popped like crazy and sounded like an SRT-4 when I was driving it.

Maybe I don't have the high pressure pump? I know there is a 255 and 255 high pressure pump.

Bahhhhhaaaaaaaaaaaahhhhhhhhhaaaa..... Well my dyno proves there's nothing wrong with my feul set-up also track times prove a welll prepared car....

At least one of us has a well prepared car

I drive a DSM daily and the only thing it's well prepared to do is break down consistently... ah well... my fuel pressure is accurate though

To add some info to the thread- I put my AFPR on today, the stock fpr was being overrun. I was sitting at 40psi at idle with the vaccum line attached (should be 26-28 according to haynes). Now have it set at 30 psi baseline, swapped plugs (very black and obviously rich). Car runs smoother, better idle and less hesitation in low rpms. I'd highly suggest an afpr when running a 255 pump although you can live without it (got 29mpg with stock fpr). My gas mileage should go up to 35mpg now hopefully.

Hmm... I'm pretty sure stock fuel pressure with vacuum line disconnected is around 37-39psi. When you connect the vacuum line, it'll drop down some. A 30psi baseline sounds a bit too low.

Other way around, pressure goes up when the line is disconnected. And I got all the specs from my manual on baseline fuel pressure.