Low fuel pressure after installing new fuel pump

[Gilkey96]

Hello, first time posting here. I have an 03 Chevy 1500HD with the 6 liter gas engine. The truck ran fine until the fuel pump died on me and had to get it towed. Replaced the fuel pump with a precision pump from O’rileys and changed the fuel filter while I was there. The truck will run and drive now but it wants to idle around 500 rpm when in drive and it tries to stall if you touch the gas. It drives fine though, just doesn’t want to idle. Put a fuel pressure gauge on the rail and only have 50 psi. I guess these trucks should have 55-62 psi to run right. I thought the regulator might be the issue because when I would unplug the vacuum hose it jumped to 56 psi. Replaced the regulator and no change. The only thing I can think of is that I was sold a faulty fuel pump. Any help would be appreciated because I’d rather not have to take the bed off again if I don’t have too. Thank you!

[garagerog]

Replace the fuel pump with an OEM AC-Delco.

[davester]

If your truck has a vacuum line, that means it has the fuel pressure regulator on the fuel rail.  This also means there's a inline fuel filter along the inside of the frame rail, below the driver's seat.  Maybe replace that and check FP again/.