Lb7 fuel pressure problem

Matthewpollard1990

New member
May 10, 2021
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I have a 2002 2500 chevy with 6.6 lb7. Injectors replaced about 10k miles ago. No fuel in oil. Heater hose broke on the firewall blew antifreeze in the ficm. Dried it out for it back running. Took it on a trip today the truck has no power. Surging going down the road. At idle I can hear injectors change tones. Has a slight duel knock I can make go away if I back fuel pressure down at idle with tech 2. Replaced the ficm. Still have all the symptoms. Pics are with truck warm and at idle. Possiably a fuel pressure regulator or relief valve. Also desired fuel pressure at idle jumps from 4900 to 5600. Has code p0094. Has a long crank to get running. Soon as I cut motor off the actual pressure drops to 158psi
 

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2004LB7

Well-known member
Dec 15, 2010
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Norcal
Have you checked to see if you are getting air in the lines? The FICM does have fuel lines running through it so you would have had to pull them off to change it out. Maybe one of the banjo bolts is not sealing properly. The crush washer is supposed to be a one time use so if you reused them that might be it
 

Matthewpollard1990

New member
May 10, 2021
6
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What makes the desired fuel pressure surge? At idle my desires will go from around 4900 to 5300 and back and forth. Have a lope at idle also and surges going down the road
 

Matthewpollard1990

New member
May 10, 2021
6
1
3
No lift pump. Has a new ac Delco filter new filter assembly all new rubber lines. Replaced the rubber line on driver valve cover that was kinked. Still have some problem
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
15,269
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Mid Michigan
Merged your two threads, as its the same issue.

If you do decide to replace the FPR, make sure to buy a Bosch OEM one, not a cheap Ebay chinesium one.
Also, you may want to use one of the longer Torx bits (I forget what size the bolts are) on your 1/4" ratchet.
 

ironmax

chock full of goodies
Jul 7, 2010
502
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Col. Ohio
Also check wiring going to the fpr. I had a situation where it would test fine unhooked and loose signal when connected. Happened to be a broke wire in side the sheathing at the plug.