Fuel PSI question

[87GNcospg]

i have an accufab fpr on my car. i set it to 42 line off 39 line on. when i first had it on my car(a month or so ago) i would get about 55-56psi WOT at 14-15 lbs of boost. now it will only get 51psi at the same boost. what could be causing the lower amount of fuel pressure?

 

[fast eddie]

change the fuel filter or run some zylene about three gallons in a full tank of gas,that will clean your whole fuel system for you.
Ed

 

[WarpSpeed]

The metal vacume tube that the FPR rubber hose attaches to may be partically clogged,,, or you have a vacume/pressure(under boost) leak somewhere.

 

[Paul Clark]

How fast does the regulator respond when you remove the hose and/or adjust the pressure.
I have the same regulator and mine now is very sluggish responding to any adjustments.

 

[OneLethal87GN]

When I remove my vacuum line the pressure doesn't go up or down. I found that weird since I've seen where they're supposed to go down quite a bit when removed with the car running.

 

[87GNcospg]

i use a few gallons of xylene in the car every week.

ever since i installed the accufab fpr it has been very slow to respond to any adjustments made to it. sometimes i can turn it a full turn or so and it will still be at its starting pressure. when i take the hose off it is usually pretty quick to jump up a few psi on the gauge. there have been a few times when the pressure doesnt change at all when i pop the line off but it hasnt happened recently.

i will check the metal line going from the regulator.
thanks everyone.

 

[87GNcospg]

well, i still havent changed out the fuel filter. it started to rain today when i had time to popo a new one in.
the fuel psi has started to do something else that it has never done before. i have the fuel psi set to 42 line off 38 line on. most of the time now when i let of the gas after a WOT run the fuel psi will drop to 35 and take a little while to get back up to 38. it has never dropped fuel pressure after a WOT run.
anyone else ever have this happen?

 

[Paul Clark]

Fixed my problem with a different gauge.
Yours might be tired also.

 

[87GNcospg]

i have a brand new digital nordskog gauge. i hope it isnt the gauge. damn things are kind of pricey.

 

[87GNcospg]

how do you know if a fuel pressure regulator has gone bad?

 

[77tech9]

Xylene sometimes can be very bad inside your fuel system. Is your FPR leaking at all? that is usually a sign that the diaphram is shot.

It might be the guage, try a fuel rail mounted mechanical one. If your coming down to races on friday i'll let you use mine. Mine responds almost instantly when turning the screw.

 

[XLR8]

Does the car seem to be running different? Is the gauge electrical or mechanical? Do you have another FP gauge you can hook to the fuel rail to verify the readings?

 

[87GNcospg]

sometimes the car doesnt pull as hard as it normally does. it is a digital gauge and it has a sending unit that i mounted next to the passenger side of the plenum. well if i go to PMI friday i can use 77tech9's gauge to see what is going on.