Duramax Diesels Forum Truck of the Week
  #1  
Old 01-12-2009, 06:30 PM
55shoebox 55shoebox is offline
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Default LB7 fuel pressure sensor

I would like to check my fuel rail pressure sensor does someone have the specs on how to check it (ohms). If possible is there a way to check the fuel regulator / solenoid?? I think i have reduced my problems to either of these and was hoping to check them besides just replacing the parts. Thanks Tracy

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Old 01-14-2009, 09:12 PM
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Only way I know to check it is with a TECH II or EFI Live. I am guessing your talking about the fuel pressure regulator.

If it was a sensor, you would light a CEL.
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Last edited by scramHD; 01-14-2009 at 09:13 PM.
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Old 01-14-2009, 10:16 PM
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to test it disconnect the FRP sensor with the truck runnin and observe the RP, if it goes higher than 175MPa then replace the FRP sensor.

idf it dont then thee might be a short to a ground in the wiring for the FRP sensor.
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Old 01-15-2009, 02:11 PM
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Uh, hes got to have TECH II or EFI to observe rail pressure right? Dont think he has the RP gauge.

What symptoms is the truck having?
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Last edited by scramHD; 01-15-2009 at 02:19 PM.
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Old 01-15-2009, 09:28 PM
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Quote:
Originally Posted by scramHD View Post
Uh, hes got to have TECH II or EFI to observe rail pressure right? Dont think he has the RP gauge.

What symptoms is the truck having?
yup one of them
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Old 01-16-2009, 08:11 AM
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Ask Henry if he hasnt allready posted it Look in the GM specs section

Look for big flucuations in the milli amps of regulator Des VS Actual
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Old 01-16-2009, 07:25 PM
55shoebox 55shoebox is offline
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The truck runs ok at idle but as soon as you roll onto the throttle it stumbles and feels like it is dropping cylinders. I have changed injectors - primed the fuel system ALOT and have had several people try to figure it out with no luck. I don't have monitoring equipment, or a pressure tester for that high of pressure. I have had several people tell me the next thing to check would be the rail pressure sensor or the regulator on the pump. Any help will be appreciated - Is there anybody on here that is in SE WA state that i can bring the truck too?? Thanks Tracy
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Old 01-16-2009, 08:06 PM
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fuel filter
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Old 01-16-2009, 08:08 PM
radvans radvans is offline
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Normally a bad fpr will have a slight surge at idle and be fine when driving.

There are some handheld tuners that can show rail pressure, ppe for example.
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Old 01-16-2009, 08:45 PM
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changing out the fca with a new one might help
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Old 01-20-2009, 06:13 PM
55shoebox 55shoebox is offline
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Yeah changed the fuel filter twice cut them open even first one was pretty funky next one was clean. FCA ? dont know what this is - i am kinda a newbie to all the diesel terms. I dont have a tuner or really know anybody who does - if i need to take it somewhere i will, any help and or suggestions will be help. Thanks Tracy
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Old 01-20-2009, 10:13 PM
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FCA is commonly referred to as the fpr. its on the cp3 it has 2 wires coming out from it

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Old 09-15-2011, 12:19 AM
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Quote:
Originally Posted by 2500HeavyDuty View Post
to test it disconnect the FRP sensor with the truck runnin and observe the RP, if it goes higher than 175MPa then replace the FRP sensor.

idf it dont then thee might be a short to a ground in the wiring for the FRP sensor.
do you know where the ground is for that wire?
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Old 11-22-2011, 01:12 PM
JSmitty JSmitty is offline
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Im currently having the same issue, Did you ever figure out what fixed it?
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