turbotime

Ok my fuel pressure is acting weird... I am running precision 780cc with walbro 255hp and b&m commandflo fpr. At idle my fuel pressure is 48-50psi, if i give it gas from the throttle body i see fuel pressure drop to 42psi as throttle increases then back to 50psi-ish once i let go? Is this normal?

Also when i turn the car off psi drop immediately to 30psi, on my old setup it would stay at 45-50psi and slowly go down over the period of a few hours, on this one it just instantly drops...

I was thinking maybe a leak somewhere but it must be very small cause i cant see or smell gas coming from anywhere... ideas?

97grnrs

are u trying to lower FP ?

turbotime

no im not trying to do anything with it im just trying to determine if how mine is acting is normal.

If it idles at 48psi and i turn off the car shouldnt it stay at 48psi and slowly come down? Mine drops to around 25psi the second i turn the car off...

If I squeeze the main fuel line coming from the filter to the rail it increases until i let go; i kno u cant use the commandflo to lower fp

97grnrs

i dunno.. i modified my b and m regulator and when i shut my car off it drops to 0 almost instantly..

thomas@LPS

the stock diaphragm will not bypass enough fuel w a high pressure fuel pump which results in high idle fuel pressure. but when u accelerate the injector duty cycle goes up an the regulator doesnt have to bypass as much fuel thus drop in fuel pressure occurs. same thing happened to me when i put my 255 walbro on. i just got a new fpr problem solved. hope this helps u out.

boosted k20

B&M FPR are garbage. i would NEVER run them in a turbo application. i had two of them that did the exact same thing : dropped pressure when revved up. pressure should increase with rev (vacuum/pressure change) get urself an external regulator like aeromotive or even a AEM

turbotime

do you think that could be the reason that my car idles RICH sometimes and 13/14 other times? Also if i press the gas just a lil like going from a stop the car sputters but normal driving is fine

rorik

I just use a drilled stock regulator with my walbro..(as per endyn's instructions) I'm not baller enough to get a better unit.. The fpr should always maintain a certain differential pressure between the IM and the rail, if yours doesn't do that consistently, get rid of it..

turbotime

what do you mean by drilled stock one? You drill the diaphram?