I just installed a Walbro 255 from Racetronix in my '91 Z28 with a 355 and P600B. I still have the ATI booster pump too. I started the car after installing the Walbro pump and my F.P. gauge maxed out. I have a aeromotive regulator on the return line, the stock F.P.R. is deleted, and the gauge is right on the regulator. I think my gauge is junk now because I took it off and it still registers 20 psi unhooked. Is anyone using these two pumps together?

 

I had the same combo(but with the stock fpr) with no problems. Is your fpr adjustable? Do you have the stock fuel rails if so check the pressure at the rail. May also wanna check your return line too.

 

i use 2 pumps like that, with an adjustable afr, your regulator should not be on the return line though...

 

I have a walbro 255 with a kenny bell boost-a-pump. works excellent for me, no problems

 

I wasn't too sure about the FPR on the return line. The Aeromotive instructions say to install it between the fuel rails. Thats not really possible with the stock TPI rails. I researched it and I read on some forum that you can put the regulator on the return. Before I swapped the fuel pumps it was fine and I actually drove the car for the first time with the supercharger, but it was lean on the bottom, so I'm working on getting it more fuel. This is my first time playing with a supercharger, so I'm learning as I go. The motor is a 355 with Trickflow G2 heads, Comp cam 220I/224E at .50 110LSA .475 on both sides for lift with 1.5 Trickflow roller rockers, stock TPI with mild plenum work and 24lbs Bosch 3's. I'm using the FMU for now, but plan on larger injectors and a ECM that reads boost. I also have a FAST wideband in the car. I attached a pic of the FPR setup. I would appreciate any info or thoughts anyone has on this mess I got. Thanks