Hey, a little background on me and my project car...

I'm John. I live in Westchester county, NY. I own a '92 Camaro with an LT1 swapped into it. The engine has fully ported and polished LT4 heads with matched intake, 236/242 cam, 30 pound injectors, solomon tune, TPIS fuel pressure regulator, Walbro 255LPH in-tank pump from summit, 3/8" braided line, headers, exhaust, suspension, etc... All good for 500hp more or less.

The problem I have been running into is this:

My fuel pressure falls off after running the car about 20 minutes and it falls off around 5000RPM. I changed the pump to another new Walbro 255LPH pump and I checked the filter etc. MY fuel pressure is set to 43.5PSI with vacuum line off the reg. and it's fine until I get on it and push it beyong 5K RPM. Should I be running a twin-pump setup? HAs anyone else experienced this with Walbro pumps? If anyone can help, I'd greatly appreciate it. Thanks.

 

whats your pressure dropping off to around 5K and above? Get a gauge in the car to check it out.

Also check into a wb02 setup so you can see everything thats going on.
How about your plugs? Do a quick Pull to 5k rpm shut it down. check your plugs.

 

It goes gradually all the way down to nearly zero, almost like the pump is maxing out or like voltage is dropping. I haven't hooked a volt meter up to see what voltage is doing, but it sure would be odd for voltage to taper off like that. It's leaning out at top end, the pcm picks up a lean code and it messes up how the car runs.