Fuel Pump or Fuel Pressure Regulator? (p0171,p0174)
11-24-2015, 06:37 PM
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Fuel Pump or Fuel Pressure Regulator? (p0171,p0174) hope this is the correct forum for this post but here it goes.
truck is a 90 k5 with a 5.3 out of an 04 silverado (STOCK), ep381 fuel pump
Recently I had a p0171 and p0174. I first began a search for a vacuum leaks, could not find one. so I did a lot of reading last night and decided to borrow a fuel pressure tester from the auto parts store tonight and test my fuel pressure.
at idle 40 psi. I disconnected the vacuum line from the regulator and I still had 40 psi. when I shut the truck off pressure dropped off immediately. had my wife come out and help me with another test, I took the fuel cap off and and had her turn the ignition of so the pump would prime. I could hear fuel splashing in the tank.
my theory is either the rubber hose that connects the fuel pump to the delivery line is split or partially disconnected inside the tank or the fuel pressure regulator on the rail is stuck open (letting fuel by)
I plan to do another test tomorrow night. I'm going to isolate the fuel send line and check pressure there.
Am I moving in the right direction? are the symptoms described not pointing to regulator?
truck is a 90 k5 with a 5.3 out of an 04 silverado (STOCK), ep381 fuel pump
Recently I had a p0171 and p0174. I first began a search for a vacuum leaks, could not find one. so I did a lot of reading last night and decided to borrow a fuel pressure tester from the auto parts store tonight and test my fuel pressure.
at idle 40 psi. I disconnected the vacuum line from the regulator and I still had 40 psi. when I shut the truck off pressure dropped off immediately. had my wife come out and help me with another test, I took the fuel cap off and and had her turn the ignition of so the pump would prime. I could hear fuel splashing in the tank.
my theory is either the rubber hose that connects the fuel pump to the delivery line is split or partially disconnected inside the tank or the fuel pressure regulator on the rail is stuck open (letting fuel by)
I plan to do another test tomorrow night. I'm going to isolate the fuel send line and check pressure there.
Am I moving in the right direction? are the symptoms described not pointing to regulator?
11-24-2015, 07:10 PM
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I think those codes are same I had on a 01 Yukon 5.3. I found that intake gaskes had the rubber seal had split but had to take intake off to find it. This case of yours fuel pump pressure not rite. I did everything I could think of to fix it. I like you thought of pump as mine didn't run. When torn apart it had the strainer fallen off sucked in crap. Did plug wires/plugs/ fuel filter & changed injectors with another used set. Intake gasket was last thing I did night & day difference, no more codes ran great.
11-24-2015, 08:14 PM
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interesting, i will keep that in mind if the codes persist after i fix the fuel pressure issue.
a helpful bit of information would be knowing whether or not the FPR should allow fuel by during prime. I read on another post i should see 60+ psi and holding during priming
a helpful bit of information would be knowing whether or not the FPR should allow fuel by during prime. I read on another post i should see 60+ psi and holding during priming
11-25-2015, 08:05 PM
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I believe it takes 58lbs fuel pressure for normal driving. You don't have gas coming out of vacuum port of regulator do you? If so regulator is shot. Diaphram is bad in it then. Check vacuum line for vacuum when running---see if bad hose?
11-26-2015, 05:46 AM
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hope this is the correct forum for this post but here it goes.
my theory is either the rubber hose that connects the fuel pump to the delivery line is split or partially disconnected inside the tank or the fuel pressure regulator on the rail is stuck open (letting fuel by)
Am I moving in the right direction? are the symptoms described not pointing to regulator?
my theory is either the rubber hose that connects the fuel pump to the delivery line is split or partially disconnected inside the tank or the fuel pressure regulator on the rail is stuck open (letting fuel by)
Am I moving in the right direction? are the symptoms described not pointing to regulator?
http://www.racetronix.biz/items.asp?...atus=0&Tp=&Bc=
01-18-2016, 08:34 PM
#6
Second on gaskets ... I have 03 Silverado with 5.3 L. Just went threw this, had same codes. Checked fuel pressure , had 45 psi. Thought it was low, put walboro 255 in it. Have 58 psi now, codes still popping up. Did intake manifold gaskets and truck is fixed. 90000 on motor.
