Fuel Pressure Regulator question

plastic_phork · Sep 3, 2005

Right now I have a walbro 255 stock injectors and stop fpr. I start the car and my fp gauge shows 40psi stock is 37psi from what i've read. Now when I rev the engine the fp goes anywhere from 40-65 it depends on how much the throlle is open but the most i've seen it go was 65 I didn't want to take a risk and run reallllllllyyyyy rich and not be able to burn the fuel. Well the plugs are fouled out=( 3 sets of ngks have gone in and out of this car in 5 hours to figure this out.

Now here is my question. Under boost what should the fuel pressure be at? I am only running 10psi if I bought an adjustable fpr and set it to 37psi (stock) all the time would I be able to boost to 10psi fine on the stock turbo, stock injectors, and a walbro 255?

Should the fp always be at 37psi or what? I need some help on this so any information is greatly appreciated.

NOSLO2PT0 · Sep 4, 2005

Fuel pressure should rise close to 1:1 ratio with boost. If your base fuel pressure is 40psi, and you run 15psi of boost. Your fuel pressure gauge should read 55psi. Take base, then add amt. of boost, that's what FP gauge should read.

-silencer- · Sep 4, 2005

Walbro 255 and stock FPR? That's your problem. Get an AEM/Aeromotive AFPR & FP Gauge.

plastic_phork · Sep 4, 2005

I don't think that the stock fpr is working since when the car barely boosts at all just mash the gas the fp jumps to anywhere from 40-65. Would that mean its broke? Shouldn't the stock fpr regulate it to a certain amount?

timloomis · Sep 4, 2005

why are you only running 10 psi?

urcnjoe · Sep 4, 2005

Your stock fpr is probably working but it is being over run by your 255 pump. Take others advice and purchase an AFPR. Also is the gage your using a liquid filled type???
If so the temperature of your engine will make the readings fluctuate, so you need to set your pressure and leave it alone. Start looking for an adjustable fuel pressure regualator.

oldman · Sep 4, 2005

plastic_phork said:
Right now I have a walbro 255 stock injectors and stop fpr. I start the car and my fp gauge shows 40psi stock is 37psi from what i've read.

Problem is, the 37psi stock pressure you speak of is without the vacuum line hooked up. Assuming you're idling at 18HG = -9psi, with the vacuum line hooked up the fp gauge should read 28psi (1:1 37-9), not 37psi. If your gauge is reading 40psi at idle, you're overrunning the stock fpr by 12psi (40-28), not 3psi (40-37) as you originally though. Get that afpr like everyone have suggested.

plastic_phork · Sep 4, 2005

Can I buy the b&m fuel pressure modifier and fix my problem? I don't really have that much money to shell out to buy a fuel pressure regulator.

oldman · Sep 4, 2005

plastic_phork said:
Can I buy the b&m fuel pressure modifier and fix my problem? I don't really have that much money to shell out to buy a fuel pressure regulator.

Waste of money. The reason for stock fpr overrun is because the return orifice on the fpr is too small to bleed off the excess fuel generated by a bigger pump like 255. The B&M command Flo modifier does not replace the return orifice and the result will still be the same.

-silencer- · Sep 4, 2005

What oldman said.

With a fuel pump larger than the 190 Walbro you need a good AFPR to handle it. The Aeromotive AFPR is $142 @ slowboyracing.com or the AEM AFPR is $175 @ extremepsi.com.

plastic_phork · Sep 4, 2005

Is there a kit I can buy that is just a bolt on kit to fix the problem? Just something that is easy to bolt on and fixes the problem. Prior to this car i've never messed with anything fuel related other then taking out and installing fuel pumps.

-silencer- · Sep 4, 2005

plastic_phork said:
Is there a kit I can buy that is just a bolt on kit to fix the problem? Just something that is easy to bolt on and fixes the problem. Prior to this car i've never messed with anything fuel related other then taking out and installing fuel pumps.

Yeah.. it's called an Aeromotive AFPR. It's easier to install than a fuel pump..

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Fuel Pressure Regulator question

plastic_phork

NOSLO2PT0

-silencer-

plastic_phork

timloomis

urcnjoe

oldman

plastic_phork

oldman

-silencer-

plastic_phork

-silencer-

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