Duramax Diesels Forum Truck of the Week
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Old 12-07-2019, 07:14 AM
Mixxter61 Mixxter61 is offline
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Default LB7 Surging Problem

I bought a 2003 LB7 with 293000+ miles on it. The truck hadn't been driven in about 8 months but started right up. No issues except it surges sometimes. The rpm jumps about 200 in different rhythms. Sometimes quicker than others. It hasn't affected the performance of the truck. Fuel mileage and power don't seem affected. I've read about a fuel pressure regulator. Can anybody give me ideas where that is located and if that would be the issue? Thanks
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Old 12-07-2019, 09:49 AM
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2004LB7 2004LB7 is offline
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It very well could be the issue. It is located on the CP3 which is tucked down in the valley of the engine and near the front side. Not too easy to get to. If you have small hands and the right tools you can swap it with the CP3 in place. Otherwise it is easier to pull the CP3

I would try easy things first like doing a filter change and maybe some fuel additive
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Old 12-07-2019, 01:19 PM
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Moved to LBZ section of Hard Parts.



Please try to post tech questions in the tech areas, not in Introductions. Thanks.
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Old 12-07-2019, 01:39 PM
gmac32 gmac32 is offline
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I think you need to move it to LB7 section
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Old 12-07-2019, 01:50 PM
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Geezus H....I read it as LBZ. I had just been looking at the "LBZ loose wires" thread.
Thanks. Got it right this time.
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"BBT" -- 2003 GMC CC/SB 4x4 12.14@111.15
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Old 12-08-2019, 09:37 AM
Mixxter61 Mixxter61 is offline
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2004 LB7 What is a CP3?
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Old 12-08-2019, 09:43 AM
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Quote:
Originally Posted by Mixxter61 View Post
2004 LB7 What is a CP3?
The 01-10 Duramax comes from the factory with a CP3 (high pressure fuel injection pump). One thing that can be is adding 2 stroke oil to your tank at the ratio of 1 quart to every 6 gallons. This has been shown to lubricate your fuel system and temporarily or even "permanently" fixing your issue. Depending on your mileage it may be tbe prudent approach to replace the entire CP3 with a new Bosch unit.
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