I am trying to help a buddy who just installed the Holley Pro Black fuel pump. Car idles fine with 7psi of pressure on the dual feed carb pressure gauge. But at about 3500 rpm it revs but does not pull like it should. Checking the plugs it is running too lean after a short run. We know he is losing fuel pressure but why. We checked with another gauge to see if the carb gauge is working and it is. The pump is wired with 10 gauge wire to a toggle and back to the battery in the trunk and is grounded fine. What could be causing the lean condition?

 

A lean condition surfacing that fast doesn't really sound like a fuel pump. Did you happen to think maybe it was a jetting problem. Unless it was fine before and the problem surfaced after the new pump, why would you point your finger at the pump? It is possible that you got a bum pump. Also, just b/c the idle pressure looks good doesn't mean squat. You need to monitor the fuel pressure for an extended WOT run, especially in high gear/high rpms. Thats where you'll see your fuel pressure drop if your pump isn't keeping up.
...ed

 

Yeah, you gotta run an in-dash fuel pressure gage with a system like that to monitor it. I use ACCEL's with the isolator and have it installed in my dash. Nice.

 

The only thing changed was pump, 3/8 aluminum line from factry fuel lines and a mallory pressure regulator. We'll run a gauge and see if the pressure is dropping like I suspect. Thanks for the help so far.