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Re: engine runs fine have only limited pressure weak
Check to see what your inlet pressure is. If your inlet pressure is lower than what is recommended, the pump will put out more than it is getting into it. Also check to see if it has an inlet screen. If it does, it may be plugged up, & need cleaning. The only other thing would be the pump itself is worn out, or has something jammed in the impeller, not knowing how old it is.
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It's P0171 & P0174 not Pc 171 & Pc174 ! The engine computer has detected a lean condition ! That mean's it's not getting enough fuel or has a vacuum leak , bad O2 sensor ! fuel pump getting weak . fuel pressure regulator weak !
P0171 - System to Lean (Bank 1)
The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. Refer to Section 1 , Powertrain Control Software, Fuel Trim for more information.
Air Measurement System
EVAP canister purge valve leaking (when canister is "clean").
Fuel supply line restricted.
Fuel rail pressure sensor (incorrect reading).
Air Induction System
Air leaks after the MAF.
PCV system (leak, valve stuck open, etc.)
Improperly seated engine oil dipstick.
Exhaust leaks before or near the HO2Ss (exhaust manifold gasket, mating gaskets, etc.).
EGR valve tube/gasket leak
EVR solenoid vacuum leak
Secondary Air Injection
Damaged/malfunctioning secondary air injection system (mechanically stuck valve).
P0174 - System to Lean (Bank 2)
The Adaptive Fuel Strategy continuously monitors the fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. Refer to Section 1 , Powertrain Control Software, Fuel Trim for more information.
See Possible Causes for DTC P0171.
See Diagnostic Aides for DTC P0171
View Freeze Frame Data to determine operating conditions when DTC was set. Observe LONGFT1 and 2 PID(s). Refer to Section 2 , Adaptive Fuel DTCs Diagnostic Techniques for more information.
Clogged filter, NOTE: sometimes a fuel pump will run, but is still too weak to run an engine properly. You can go ahead and replace the pump and then rule it out as being bad, or check the fuel pressure and see if it is within the proper limits.
This sounds like a weak fuelpump, and take a while to build up pressure, the starting fluid get the engine running until the pump builds up pressure, i would have the fuel pressure tested and i think you will find that its bad. good day.
Gonna give you a list of items that I've come accross with this vehicle same problem.
Hope it helps!
EGR stuck open
battery and cables ( weak and corrosion)
Fuel pressure regulator (stuck open)
PCV valve defective
Fuel pump defective check ball ( little to no residual pressure)