Well the story goes that I recieve my fuel pump and install it and everything but everytime I would go out to my car to crank it, it would take it about 10 seconds before it would start like it was having to re-prime the fuel lines. But after it started, it ran amazingly well. Probably smoother and more powerful than it has since I have owned it. Well someone on here told me that the reason it would start normal is probably becuase of the o-ring on the fuel pump. Well I took it all back out and fixed the o-ring. Now the car will start up good and everything but it runs like garbage when I am 3/4 throttle or above or when I am in boost. Like if I go from a stop and try to wind out first it will just start spittering and sputting really bad and it is like the rpm's wont climb any higher once it is in boost. I have since taken the fuel pump back out and checked everything again, but everything looks fine, and everything is hooked up good. Could it just be a really bad boost leak, or is my car getting too much fuel or not enough fuel perhaps? Or could it be my crappy 1st gen exhaust manifold that has about five big cracks that leak air when the car is just idling? But it doesnt make sense to me since it ran really good but it just wouldnt start right up, but now it starts up fine, but doesnt run good! Any help would be greatly appreciated.

P.S. It is a Walbro 255lph fuel pump running stock boost. (12psi). I have no other fuel modifications.

Overruning stock fuel pressure regulator FTW

Wow, talk about one of the most newbie quesions EVER. Search and you would have found your answer.

When you put in your big and bad Walbro 255 pump, you didn't realize that it flows a LOT more fuel then stock, and now your stock Fuel Pressure Regulator (FPR) cannot control the amount of fuel it is being fed. Thus, making your car run super rich, because boost, and fuel pressure rise at a 1:1 ratio.

Now, to fix your problem, your going to either need to go back to a stock pump, or get a Walbro 190 pump. Your stock FPR can handle that. Or, the best thing to do is to go out and buy a AFPR (Adjustable Fuel Pressure Regulator) that can handle the new amounts of fuel being fed to your car, thus not making your car run rich, and back to good again.

But please search next time. I see this quesion almost every day. It gets annoying to see it again. "Search" Thats what its there for.

Classic fuel pressure regulator overrun.

Your fuel pressure is probably around 60psi right now. That's about 20psi too high. Get an adjustable fuel pressure regulator and crank that pressure back down to 43psi where it should be. Your car should then start and run just fine.

Thanks for your help guys. It is not that I am a newbie or that I dont have the slightest idea about cars, it just that I am way too lazy to search. Dont ask y, I know I could find the answers and find them quicker. I just dont like to search. And I was actually thinking that this was my problem, but I just wanted to make sure. Because as I stated before I have some boost leaks and an exhaust manifold that is cracked beyond repair and I just wanted to make sure that these weren't contributing to the cause. But thanks again for your help guys. I will be purchasing a fuel pressure regulator tomm. Has anyone had any experience or input on a B&M unit. Because a performance shop around here carries that one and I could have it tomm. instead of having to wait on one to ship. Or do you think I should just flow with the crowd and order and aeromotive unit online? Also what else do I need to purchase to install an AFPR? Like fittings, etc., or do they just bolt right up? Any extra fuel lines I might need or anything? Once again thanks for your help!

-Keylan-

topnotchgsx said:

it just that I am way too lazy to search. Dont ask y, I know I could find the answers and find them quicker. I just dont like to search.

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topnotchgsx said:

Has anyone had any experience or input on a B&M unit.

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We're here to help, not spoon feed. You're going to have to quit being lazy, and start searching to answer you're qustions. (especially the one's that have been covered time after time )

The B&M is not what you're looking for......
http://www.dsmtuners.com/forums/showthread.php?t=186834

99gst_racer said:

We're here to help, not spoon feed. You're going to have to quit being lazy, and start searching to answer you're qustions. (especially the one's that have been covered time after time )

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It's such a turn on where you put your foot down.

or, you can go out and buy a SAFC and tune it(fuel trims). that'll make your problems go away as well.

xad_theman said:

or, you can go out and buy a SAFC and tune it(fuel trims). that'll make your problems go away as well.

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A S-AFC will not be able to tune out the irregular fuel pressure that the 255 causing. The only solution is to get an AFPR.

larsrya8 said:

A S-AFC will not be able to tune out the irregular fuel pressure that the 255 causing. The only solution is to get an AFPR.

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This is correct. The degree of fpr overrun is based on the amount of fuel your engine is consumming at any given moment, load if you will. Since load is based on many factors, throttle position, gear, rpm....etc, it's impossible to tune out fpr overrun because the change is a non-linear one.