Fuel pressure - How low is *too* low?

[mjwsw]

[ 98 GMC Suburban / 5.7L / 2WD / 183K ]

Greetings,

I recently started experiencing very poor acceleration at wide open throttle, and/or near wide open throttle, for instance when accelerating onto the on-ramp of a highway. Moderate acceleration is fine though and at an idle, the engine is silky smooth. I've already eliminated many possibilities, but I'm presently suspicious of fuel pressure.

The specs for this vehicle are supposed to be 55-60psi, and 66 at WOT. I put a guage on it and see that at idle it's about 55, mild to moderate acceleration it's about 58, but it drops to about 52 at WOT.

My question is this... Is 52psi at WOT low enough to possibly be causing my problem? I replaced the pump about 2 years ago but never measured the pressure before this. Also, can the ECM control fuel pressure (measured at the test port)? Could the pump be good, yet the ECM be preventing it from supplying the specificied 66psi at WOT? Thanks in advance.

--mike

[wafrederick]

GMs will not run under the lowest fuel pressure and this is true.What brand was the replacement fuel pump?Airtex,Carter and fuel pumps from Advanced and AutoZone are junk.Delphi is the way to go,from your nearest Carquest parts store or the dealer.

[maxwedge]

True on the FP brand issues, Carquest now carries Delphi, but you must specify, also fresh filter? Pcm does not control FP on that truck, engine vacuum is the primary load control and the pressure regulator.