fuel pressure is over 100psi, help!!!

Duenazn · 08-19-2010, 10:01 PM

Ok guys i've searched here and on google to find the same issue but no response on the fix. I have a 240z with the sr20det blacktop, the car sat for over 4 years and I just got it running a couple weeks ago. I installed a wideband o2 to keep tabs on my AFr's and yea run way too rich, idle is not too bad at about 13.5 but once I give it a slight raise in rpm i'm looking at 12.1 to about 11ish. I cleaned my MAF sensor, cleaned the AICV, swapped my FPR for the NISMO and i'm still getting 100 psi, my gauge pegs out at max. I checked to see if my return line was clogged and its free. My last resort was to check my pump (walbro GSL392 255lph) and its pushing 100+psi right from the outlet. Funny cause on the pump housing it says 60 psi max. Is my fuel pump the culprit here? The engine is stock with the 370cc injectors the only upgrade is the walbro pump and Nismo fpr, I even ran the engine with no fuel regulator just a hose and still 100psi+. Was even thinking my return line was too small, seriously it's like an 1/8" stock 240z crap. I bypassed it to rule it out with a hose straight from the FPR to a gallon. I'm stumped guys, yes the pump as for the rest of the car sat for over 4 years. This is my first post on here and yes I searched with no luck.

xavi1320t · 08-19-2010, 10:24 PM

Quote:

Originally Posted by Duenazn

Ok guys i've searched here and on google to find the same issue but no response on the fix. I have a 240z with the sr20det blacktop, the car sat for over 4 years and I just got it running a couple weeks ago. I installed a wideband o2 to keep tabs on my AFr's and yea run way too rich, idle is not too bad at about 13.5 but once I give it a slight raise in rpm i'm looking at 12.1 to about 11ish. I cleaned my MAF sensor, cleaned the AICV, swapped my FPR for the NISMO and i'm still getting 100 psi, my gauge pegs out at max. I checked to see if my return line was clogged and its free. My last resort was to check my pump (walbro GSL392 255lph) and its pushing 100+psi right from the outlet. Funny cause on the pump housing it says 60 psi max. Is my fuel pump the culprit here? The engine is stock with the 370cc injectors the only upgrade is the walbro pump and Nismo fpr, I even ran the engine with no fuel regulator just a hose and still 100psi+. Was even thinking my return line was too small, seriously it's like an 1/8" stock 240z crap. I bypassed it to rule it out with a hose straight from the FPR to a gallon. I'm stumped guys, yes the pump as for the rest of the car sat for over 4 years. This is my first post on here and yes I searched with no luck.

By any chance did you try turning down your regulator? When I bought mines and thru it in I didn't have a gauge then when I got one it was the same, way over 100 psi of fuel. Try that first turn the screw on the regulator counter clockwise or towards the left in other words.

Duenazn · 08-19-2010, 10:28 PM

I did, clockwise turning it into the FPR raises the pressure I totally unscrewed it all the way out till the screw came out. My thing is the fuel pump itself is blasting fuel and even without the FPR my gauge is pegged out. I know that undoing the screw allows more fuel to return to the tank lowering the PSI in the fuel rail so no FPR should technically give my super low PSI.

xavi1320t · 08-19-2010, 11:32 PM

Quote:

Originally Posted by Duenazn

I did, clockwise turning it into the FPR raises the pressure I totally unscrewed it all the way out till the screw came out. My thing is the fuel pump itself is blasting fuel and even without the FPR my gauge is pegged out. I know that undoing the screw allows more fuel to return to the tank lowering the PSI in the fuel rail so no FPR should technically give my super low PSI.

You know I went thru the same thing at work today. Try blowing thru your return line(try with you're own air), if you feel like you can't blow no more(no pun intended) something is blocking it. What happened today at the shop was the following, I had replaced 2 fpr and going on my 3rd and said to myself something else gotta be wrong. So I tried blowing thru the return line and felt that I couldn't anymore. Decided to pull the sending unit and all of a sudden the return line freed up. Put it back in and blockage again. Maybe theres something in youre tank impedding the flow back to the tank.

xavi1320t · 08-19-2010, 11:33 PM

Quote:

Originally Posted by xavi1320t

You know I went thru the same thing at work today. Try blowing thru your return line(try with you're own air), if you feel like you can't blow no more(no pun intended) something is blocking it. What happened today at the shop was the following, I had replaced 2 fpr and going on my 3rd and said to myself something else gotta be wrong. So I tried blowing thru the return line and felt that I couldn't anymore. Decided to pull the sending unit and all of a sudden the return line freed up. Put it back in and blockage again. Maybe theres something in youre tank impedding the flow back to the tank.

Is the pump noisy while running? I would think so if its pumping out that much pressure. Could also be your lines, the size of em.

Duenazn · 08-19-2010, 11:37 PM

yes the pump is a walbro so yea it's noisy, not noisy like a whine but more of a buzz when it comes on and it stays that way. 5/16" is what the feed line is, the return is tiny but like I said I ruled that out when I ran a 5/16" hose straight from the FPR to a empty milk gallon. It was spraying pretty good and still gauge at max.