1997 Chevy z71 5.7 vortec 4x4. Fuel problem.
Z71 5.7 Vortec. Ive been having problems with
what I believe is fuel related. Started having
troubles starting. So i changed the fuel pump and it
started right away and ran just fine for a few days.
Then Started lugging when you hit the gas and
ultimately on another cold day didn't start.
Changed the fuel pump again, to another Delphi
pump, and fuel fitler, started just fine. And ran for
24 hours before acting up again. A friend checked
the fuel pressure and said It was fine, but when I
turned it off the pressure fell to 0 almost
immediately. I started it today by clamping the
return line for fuel and cycled the pump about 10
times but when I push on the gas while running, it's
lugs and ultimately dies. My father says it could be
another bad fuel pump but before spending more
money on that, I wanted to get some suggestions.
It is sounding like leaky injectors, spider lines, and fuel regulator. Pressure dropping to 0 within 3 minutes is a good sign, It should only drop no more than 5 lbs in 3 minutes. Fuel pressure should be 56 to 63 lbs. I would do a dead head test on the fuel pump itself to verify that it is putting out 64 to 68 lbs.
I second injector assemly.
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