i have an ls motor with stage 2 crane cams, 275cc injectors, str fuel rail, walbro 255lph pump. It's all motor and the stock fuel pressure is 42psi i think. Right not i have it set at about 39 at idle.

I had it a little lower at about 37psi, but when i would be on the gas, then let off still in gear, the a/f gauge would go all lean, then i would put it in neutral to stop, come to a complete stop, it would stay on lean, and then stall. I could keep it running by pressing on the gas a little bit, but it was hesitant. I bumped the fuel pressure up to 39psi, and it seemed to help.

Does this sound like it could be the problem?

 

why do you keep your fuel pressure lower than stock? bump it back to 42

 

Sorry to butt in here.......... would having to high a fuel pressure setting cause you to bog down when starting from a stop light? or idle rough? or cause you to loose power in the top end?

Because those are my symptoms after I put in the new (ie bigger) walbro 255lph fuel pump?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JASON77 &raquo;</TD></TR><TR><TD CLASS="quote">Sorry to butt in here.......... would having to high a fuel pressure setting cause you to bog down when starting from a stop light? or idle rough? or cause you to loose power in the top end?

Because those are my symptoms after I put in the new (ie bigger) walbro 255lph fuel pump?</TD></TR></TABLE>

those are the same stuff that happens to me and i have that fuel pump too. I hope it is, or something like that, that's why i posted...

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 96integra &raquo;</TD></TR><TR><TD CLASS="quote">why do you keep your fuel pressure lower than stock? bump it back to 42</TD></TR></TABLE>

I keep it lower than stock because if you read it right i have cams, and a whole upgraded fuel system. If i was pumping out the stock fuel pressure with larger injectors/fuel pump/rail, it would be running super rich all the time.

 

What type of fuel pressure regulator do you have?


((Great now it's knocking at idle sometimes as well))

 

did u set the fuel pressure at 39 psi with the vacuum hose attached to the FPR? the fuel pressure for stock should be about 42 psi with out the vacuum hose attached. attaching the vacuum hose will drop the pressure down to about 30-35 psi at idle. at my idle, the fuel pressure is at 33 psi. then when i give it full throttle it shoots up to 42 (with vacuum hose off, it also reads 42 psi)

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JASON77 &raquo;</TD></TR><TR><TD CLASS="quote">What type of fuel pressure regulator do you have?


((Great now it's knocking at idle sometimes as well)) </TD></TR></TABLE>

I have a vortech FPR, as for the knocking, it's prolly the valves.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boosted k20 &raquo;</TD></TR><TR><TD CLASS="quote">did u set the fuel pressure at 39 psi with the vacuum hose attached to the FPR? the fuel pressure for stock should be about 42 psi with out the vacuum hose attached. attaching the vacuum hose will drop the pressure down to about 30-35 psi at idle. at my idle, the fuel pressure is at 33 psi. then when i give it full throttle it shoots up to 42 (with vacuum hose off, it also reads 42 psi)</TD></TR></TABLE>

I set the fuel pressure with the vacuum hose on, so i guess i should take it off and do it. I put it back to 42psi with the hose attached, but i'll try what you are saying to do and see if it helps.. Thanks

 

let me get this straight... unplugging the vaccuum hose will make the guage read the same as WOT, so if I unplug the hose I should set the FPR at ~42psi

 

I have the 62404 cams with afc at +10 across the board and the FPR set at 50psi and it doesn't run too rich I get about 30-32mpg also.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sleeperHatch &raquo;</TD></TR><TR><TD CLASS="quote">let me get this straight... unplugging the vaccuum hose will make the guage read the same as WOT, so if I unplug the hose I should set the FPR at ~42psi</TD></TR></TABLE>

Yes, cause at WOT, there is no vacuum in the vac lines, supposedly if you unplug the vac hose and plug it up, you get ~ 5whp in the midrange...but you don't gain anything at full throttle....some guy dynoed it awhile back

sorry 91...didnt notice the injectors

 

good point...didn't think of that...optimal FPR should be around 42psi?

I run ~46psi on mine, I may try leaning it out a little bit!

 

def try leaning it out a little bit.

I took my car to the shop and what was wrong with it was the fuel pump. I had a walbro 255lph pump and now i hafta get a new one. I was thinking about stock, but i went with a holley 190lph pump instead. HOpe this one works...

walbro

 

I'm running a Holley 255lph in tank pump, it has worked great for over a year now!!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sleeperHatch &raquo;</TD></TR><TR><TD CLASS="quote">I'm running a Holley 255lph in tank pump, it has worked great for over a year now!!</TD></TR></TABLE>

hopefully the holley 190 does the trick for me too...

 

Take your car to a dyno and have it tuned. Not to be a jerk but I was in the same boat and I took it to a dyno and had it tuned and gained 30+ whp. That was the best money I have spent. Now I just keep bustin axles!!!!!!!!!!!!!!!

 

yeah that's the next thing i'm gonna do. I found a place that's like $150 an hour, so i might split it between me and someone else and tune.