low fuel rail pressure 02 lb7 duramax - Chevy and GMC Duramax Diesel Forum
01-04.5 LB7 Duramax Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission Ect

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Old 12-08-2013, 07:42 PM   eBay Motors  #1 (permalink)
 
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low fuel rail pressure 02 lb7 duramax

Hi I have an 02 duramax that just rolled 205k miles and I have been having my check engine light come on at least once every 2-3 days and the truck will run like complete crap. It won't rev over about 1800-2000 rpms and I gotta let off the throttle in order for it to shift and yet its still hard to get it up to the state speed limit (55). My girlfriends brother in law has a programmer that gives you diagnostic codes and I plugged it in and it came up low fuel rail pressure. Would this most likely be caused from bad injectors or fuel pump?
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Old 12-08-2013, 07:52 PM   eBay Motors  #2 (permalink)
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How often do u change your fuel filter? Start simple.
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Old 12-08-2013, 08:00 PM   eBay Motors  #3 (permalink)
 
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I knew I had to change it soon then my truck started acting up so I changed my fuel filter and it straightened up til half way through the next day when it acted up again. Oh and let me throw this curve ball out there. Once it starts getting cold out like this it will lose prime to the fuel filter so everyday when I start it for the first time of the day I have to prime the filter.
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Old 12-08-2013, 08:02 PM   eBay Motors  #4 (permalink)
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First check the rubber fuel lines between the tank and the engine. GM published a bulletin that says that additives that many suppliers blend into modern diesel fuel softens the flex lines, especially on the frame near the transmission and at the fuel filter, and when the CP3 tries to pull fuel all the way from the tank the lines collapse, restricts fuel flow, and sets a low fuel rail pressure code. More common in hot weather but sometimes happens in cold weather as well. The two lines at the fuel filter are usually the first to give trouble and they're really easy to replace.
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Old 12-08-2013, 08:02 PM   eBay Motors  #5 (permalink)
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My truck looses prime if I park it on an incline motor up. I'm not sure man. Could be a cp3. Simone will chime in. Hang in there.
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Old 12-08-2013, 08:07 PM   eBay Motors  #6 (permalink)
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Quote:
Originally Posted by dylonbrabham View Post
I knew I had to change it soon then my truck started acting up so I changed my fuel filter and it straightened up til half way through the next day when it acted up again. Oh and let me throw this curve ball out there. Once it starts getting cold out like this it will lose prime to the fuel filter so everyday when I start it for the first time of the day I have to prime the filter.
With these additional symptoms it's probably not the soft fuel lines I just mentioned...
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Old 12-08-2013, 08:14 PM   eBay Motors  #7 (permalink)
 
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So what are we thinking? Maybe a new fuel pump or injectors? Or do you think maybe I just have a few injectors that are plugging up from dirt or something? I really think this has slowly progressed because when I first bought this truck almost 2 years ago now I was getting 17-18 mpg even around town. Now the absolute best I can get is about 12.5 and the occational 13 if I'm lucky.
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Old 12-09-2013, 06:44 AM   eBay Motors  #8 (permalink)
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You may want to start by rebuilding your fuel filter housing. What is the code the truck is throwing? Also do you have any smoke at idle, hard start when warm, making oil, or have you checked your balance rates?
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Old 12-09-2013, 10:37 AM   eBay Motors  #9 (permalink)
 
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I will hook it back up tonight or tomorrow and I'll get the code for ya. I'd just like to have it fixes I know that. I love the truck but its lost some power and fuel mileage. If I can't figure it out then I might look for a new one.
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Old 12-09-2013, 10:43 AM   eBay Motors  #10 (permalink)
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Good chance your cp3 or injectors are going out. Where are you located?
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