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96 GMC Suburban Fuel Pressure problem

1672 Views 6 Replies 5 Participants Last post by  Motor City Rick
I have a 1996 GMC suburban 2500 7.4 vortec that has a miss at idle. I have replaced the FPR, spark plugs, wires, Cap, and rotor and its still misses. when I connect my pressure gauge and turn the key on it jumps to around 45psi and holds but when I turn it off it falls back to around 25psi. could it be a faulty FPR or if it was the rubber hose on the fuel pump shouldn't I hear the gas running back in the tank? any help would be greatly appreciated.
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I'm working on a no-start issue on the same 96 k2500/7.4l engine/chassis combo with the same exact fuel pressure readings. i just went through these steps checking my fuel system. from what i've read, if fuel pressure holds with return line crimped, a bad fpr is indicated. however, if fuel pressure still bleeds off, the check valve in your fuel pump has almost certainly gone bad meaning the fuel pump needs replacing. to confirm this, disconnect the fuel line at the filter and install your fuel pressure test gauge in the filter's place and cycle the pump. replace the pump if it still bleeds down. if pressure holds from tank to filter, check for fuel in vacuum line from fpr and stuck or leaking injectors. mine still lost pressure immediately so i replaced the fuel pump. pressure holds better, but still bleeds down 2-3psi/minute, leading me to believe my fpr is bad as well. my burb has always ran a little rough and gotten terrible gas mileage that is commonly fixed by replacing injectors with Bosch 4-hole style so, since replacing the fpr requires removing the upper intake, i plan on swapping in upgraded injectors and a new dizz cap and rotor, if not a complete new distributor at the same time i have the intake out of the way.
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