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mastertech29, ASE Certified Technician
Category: GM
Satisfied Customers: 184
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1996 GM C1500 p/u 5.0 vortec truck parked years got to start

Customer Question

1996 GM C1500 p/u 5.0 vortec truck parked for 2 years
got to start p0171,p0174,p0300 code at first engine miss no power
replaced new tank excessive rust bad fuel, new sending unit pick up assembly with new Delphi pump, fuel filter, new spider injector assembly, both up stream O2 sensors, plugs gap .060, oil pressure sending unit, used harness at crank sensor, New Distributor assembly cap, rotor, wires, new coil checked hoses for vacuum leaks has 22 in of vacuum at pcv port constant, prime fuel pressure at 50psi running psi at 54 sprayed carb cleaner around intake and throttle body with no change of engine miss now only P0300 code with engine miss lacks power no change with MASS airflow on or off only parts not changed intake gaskets and crank sensor
Submitted: 1 year ago.
Category: GM
Expert:  mastertech29 replied 1 year ago.

Hello, My name is ***** ***** I'll be happy to help. It sound like your going to bed a new fuel pump. The 1996 vortec needs ​a minimum of 55 psi at all times or it will not give you the P0300 random multiple misfire. The P0171 and P0174 are telling you that the system is to lean or to rich. Most of the time when I see those codes together it is the intake manifold gasket, a vacuum leak. You've ruled them out worth the carb cleaner. The last thing it could be is the new fuel pump. Please let me know if you have any other questions. Thank you.

Expert:  mastertech29 replied 1 year ago.

I'm not sure if I was clear. Your isle pressure is within range but under load you need 55 psi. Thank you.

Customer: replied 1 year ago.
on the 3rd new fuel pump now.
installed one with level sensor assembly then bought a new and installed it then warranted that one out
with readings now all from different locations
compression at 180 across