Key on engine not running 55 to 65psi,should decrease 3 to 10psi with engine running at idle.
45 psi at idel fuel regulator connected 55 PSI with regulatr having an applied vachum to it. thr ost impotrsnt thimg is whern it'd running does it hold 39 PSI with key on engine off and for at least 30 seconds. once you prine the pu,pump it will not old that pressuer then you have a bad check vavce in the pump. so the pump has to be replaced, On the high end it has to read 50 psi full throttle. if it does nor rhen you have a vachum leak or your manifold pressure is not holding the correct vachum. WHich could be caused by throttle plate opening all the way or the way or there is a eaning of a vachum leak from theinyake hose or heare. ope this seld.
SOURCE: Truck bogs down when I accelerate.
I've got 260K on a 2003 4.8 Silverado. Fuel pump has caused this same problem, 1 after market fuel pump lasted 20,000, the same replacement was 30,000 miles. I made my mechanic put the correct fuel pump from GM using the VIN . The other time I was losing power at about 180K miles it was the cat converter. Hope this helps
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