Fuel Pump Question????????????

[72nismo]

When upgrading to Wahlbro fuel pump do I need to re-adjust my fuel pressure regulator and if so what is the pressure sspposed to be at on a KA-T?

[DevilMB3017]

Most of what I've read on the internet says you do. It makes sense that you would have to adjust the fuel pressure. Do you already have an adjustable FPR? I got a kit from EnjukuRacing that I am very happy with.

IIRC stock fuel pressure is around 36psi at idle?

[72nismo]

Yes i already have one that is set at 42 no vacuum / 38 with vacuum. If I remember right.

[krazydriver]

i never did on my car. It's been running with that for over 1000 miles.

Just think about it this way.The FPR regulates pressure, NOT flow. A high flow pump just increases the flow.. it will increase the available fuel at a higher pressure but it's purpose is not really to increase the pressure.

Therefore thinking of the fpr as a valve, it doesn't have to "flutter" to maintain a certain pressure, it could just open to a further degree to allow more fuel to go through the return line.

I may be completely wrong, but i read enough cases of people leaving the stock fpr and everything being fine, and it's been fine for me. So i say don't worry about it.

[bruinbear714]

No, you don't have to upgrade your fuel pressure regulator when getting a new fuel pump.

I ran my KAT @ 8psi with the stock OEM fuel system (with 555cc) without any issues.

[kouki_hmongster]

No, you don't have to upgrade your fuel pressure regulator when getting a new fuel pump.

I ran my KAT @ 8psi with the stock OEM fuel system (with 555cc) without any issues.

If the fuel pump is a high flow then it is recommended to upgrade your fpr. although stock fpr will work, you wont know how long it will last. what happened to me was i read a thread about not needing to upgrade and found myself stuck on the side of the road....for my dyno tune it was all wacked, after a certain rpm my afr was reading really rich. so anyone w/ high flow pump should get a fpr.

36psi is right where it's suppose to be while the car idle.

[480sx]

Iv always heard from a few different sources that the stock FPR wasnt up to the task of dealing with the extra volume of fuel an upgraded pump puts out. That your fuel pressure will spike when the pump cuts on. Idk, just stuff iv read on different forums about the SR and KA's FPR.

[72nismo]

FYI guys I am not using stock fpr. I have a Megan FPR. Now I replaced my fuel pump because my wideband kept reading lean when in boost.14 - 15+ afr.Now that I installed the wahlbro it is reading 12-3 when in boost so it is better but still a little lean So that is why I ask if the FPR had to be re adjusted to be able to handle the new pump. Sorry if i confused you guys.

[WDRacing]

Do you not have a fuel pressure gauge? Cause it's either good or it isn't. We can tell you to raise or lower it all day...won't do any good unless you know what the pressure is. If you DO know what the pressure is then you really don't need to ask the question.

In short, buy a gauge, check the pressure. Especially if you're having issues with the fuel.

[72nismo]

FYI , I readjusted my Megan FPR and now my wideband reads in the 11 AFR's. Now next to my next problem.

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Modified by 72nismo at 7:20 PM 9/7/2008