Fuel Pressure question

[rmflyfish]

hey folks. installed a whinepro 255 recently, now I'm running rich, (expected).

Put a fuel pressure gauge on and found I'm running about 38 lbs when at 17 inches mercury (vacuum), about 42 lbs at 0 (no boost) and I've seen it go to about 48 or 49 lbs at full boost (about 15 lbs).

I'd like opinions about these numbers. Do you think this is about what I should expect with the stock FPR and will a Spoolinup FPR solve the problem.

On the high side, do you think the stock FPR is not letting the pressure go up as high as it should?

On the low side, maybe the stock FPR can't bleed the fuel off fast enough?

I also have been told, I should be about 39 lbs at 0, 1 lb increase per lb of boost, and about .5 lb decrease for every inch mercury. Do these numbers jive with what other foks believe.

Thanks in Advance

[Hal]

If you remove (and plug) the hose, base pressure should be 36 - 38 psi.

If it's in this range, pressure is correct.

Hal

[rmflyfish]

Kool, I assume your refering to the vacuum line on the FPR right Hal.

[Hal]

yes

[hoffman]

i still have the stock fuel system in my car and heres the number i get.

idle pressure - 38-39psi
boost 0psi- 41-42psi
boost 15psi 51-53psi.

so i'd say your pretty close to the stock settings that i get. i think (i'm using the word think here :p ) that if you install a better AFPR that the boosted pressure will match closer to 1psi boost:1psi fuel pressure. so you should actually be seeing close to 57-58psi at 15psi of boosted.

am i close on this one?

[rmflyfish]

was thinking about the boosted pressure at 15 lb boost. I don't think I was there long enough to get a true boosted fuel pressure reading! Damn traffic and kids in the road etc... !

I'll have to make a high speed run up the highway tonight when I get off work.

But Art, I think you are a little high at '0 lbs' have you passed emmissions lately. I couldn't with the number I blew yesterday. Hydrocarbons was like 300 and need to be below 105 to pass.

I also like Hal's idea of blocking off the vacuum line to set the base pressure at 38/39 lbs. but of course that has to wait till I have a FPR with a twisty thing on it ! :p

Good to here from ya bud.. !

[hoffman]

yup, the car passed emissions in jan 02. maybe its a 1g/2g thing. but its always like that. but our numbers are almost an exact match as it is.

yeah, i'm still on the planet.:p

[rmflyfish]

1G vs 2G good point, i think there are some slight differences in the FP curve.. What say you Hal ?

[Hal]

yes, 1g & 2g base pressure is different.

I passed emissions by putting icky "pump" gas in the car and putting on the cat.

No changes were made in the tuning, and I passed by a wide margin.

[rmflyfish]

Hal:

Pulled and blocked the vacuum line on the FPR and I'm getting 43 lbs static pressure...

That pressure, by the way, is being checked at the top of the stock fuel filter, with a drilled and tapped banjo bolt.

Think it's time for a HP FPR ??

And, is that the way you'd set the static pressure once I get the FPR on...

Thanks for the input !!

[Van]

Classic fpr overrun...

Call Spoolinup.com. That is what I have with a walbro 255 rewired. Works well.

Yep, set your static pressure with that hose off of the fpr. I set my base fp at 38 psi.
This puts my 650 injectors at about a 65% DC at 6500rpm, top of third when she's leaned way out on race gas.