About a year ago I swapped in a Walbro 255lph fuel pump, because the fuel pump I had in there (a Walbro 255lph) was pushing too high fuel pressure and I couldn't figure out why. The car ran good, but at idle was rich. I still have the exact same problem. car idles at 60+ psi, and even though I have replaced the Miniram fuel lines with -6 AN braided line and I have replaced the Miniram fuel regulator with an Aeromotive FPR, the problem is still there...regardless of where the set screw is on the FPR, it still pushes 60+ psi, I had a small FP gauge on the fuel rail and thought it might be messed up, so I replaced it with a liquid filled one. Also, I blew the return line out with compressed air to make sure there wasn't any obstruction, and got under the car to check for a damaged return line...no problem found. Also when the fuel pump primes with just the key turned to on and the engine off, the pressure goes to around 45 psi, and then falls to 0 once the pump stops. I pulled the motor over the weekend to prep it for the D1SC Procharger im about to buy, so when I get the car back together I want to make sure that this problem is fixed. Any suggestions???

 

I'd double check that return line. Try (temporarily) running the return line over into a bucket or similar (have someone hold the line or clip it to the side so it can't shoot out under pressure). You know, just to CONFRIM that the return line on the car is or isn't a source of restriction. Never run into that problem, but that's how I'd probably go about starting to eliminate possible causes.

 

ttt

 

What would be the cause of the pressure not holding in the rail after the fuel pump primes?

 

Stock system is designed to slowly bleed down after the pump turns off. It won't hold rail pressure forever. It should hold it for a while. If it immediately drops off when the pump shuts off there are several causes which others could probably describe better than I could.

 

It immediately drops off...

 

Hi
i got a 383 stroker with the miniram intake manifold, im going with a Procharger too. i didnt like the setup of fuel rails that TPIS sold for the miniram, so i tapped fittings on the rails and ran braided hose and i used an external aeromotive FPR. My problem is the same after the fuel pump stops priming my rails wont hold pressure. My injectors are not leaking cause i kinked the return hose that goes after the regulator and pressure stayed but i release the hose and the pressure dropped immediatly
jim

 

Some/all of your injectors are leaking would be my first finger pointing excersize!

 

Well, I had a year old set of Accel 24lbs'ers on there(eww), but replaced them with a set of FMS 30lbs'ers, but the problem was still there. Right now i'm rebuilding the motor with a Procharger in my room waiting on me. I'm going to order a set of Racetronix 42lbs'ers whenever I start getting closer to being finished up, but I'd like for this problem to dissapear before the new motor gets fired up. I'll be installing the inline pump the charger came with and checking everything out before engine startup, if I have no luck I'll just have to diagnose from there...i'm debating on dropping the tank and checking inside, but I made sure everything was perfect when I installed the in-tank pump the last time. More suggestions welcome...