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Alright I have lurked forever and finally decided to post about my problems. I will start from the beginning. Truck is an 02 2500hd with the lb7 245000 miles pretty well taken care of. Fixing it for a buddy of mine. Was brought to me with an issue of not starting after warm unless you pumped the primer. Progressed to not starting unless primed. Prior mechanic rebuilt filter head with the merchant kit but did not fix the problem.
I got the truck and rebuilt the filter head again to be sure it was done right no change. I than ordered a new replacement filter head for an 06 which is just routed a little different no change. Replaced all lines going to and coming from the filter head. Replaced all lines in the valley that were dry rotted, Replaced ficm banjo washers. Replaced injectors with reman from injectors direct, replaced cp3 with pump from injectors direct also, shimmed fprv, replaced lines along firewall, replaced lines along bell housing, installed Kennedy single lift pump, removed bed and verified tank pickup was not plugged. No change. The truck will start and idle forever without issue. As soon as you get on it it will stall, starting from a dead stop laying into it at about 55 it stalls and puffs out white smoke. Shut it off and go pump primer 7 times go crank go pump seven more times and crank and it will start. It will do the same thing over and over. Bypassed filter head no change, bypassed ficm no change. What next? The only sensor that has not been changed is the fuel RAIL pressure sensor is it worth trying that just have not seen any posts about that failing.
 

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Wow, wow, wow. o_O

Have you tried throwing the kitchen sink at it? 😀

While you are clearly not a lazy person, I’m thinking a few $$$ towards a proper scan tool is in order. Actual vs requested rail pressure, for one.

At the risk of insulting your intelligence, all your symptoms, especially the need to keep priming obviously point to a low pressure side fuel delivery problem, but with all the new plumbing, bypassing, lift pump, etc. it would seem you have covered all the bases.

Mark Twain said “It ain’t what you know that gets you in trouble, it’s what you think you know that just ain’t so.”

cant recall where all the LP fittings are, but is there a connection, after the FICM and before the CP3 where you can break in and observe fuel delivery into a container? Also, double check output pressure of the lift pump. I believe that since the CP3 operates as a vacuum pump to pull fuel from the tank, it becomes very unhappy (symptoms, anyone?) if fuel pressure exceeds a few #.

Best wishes and keep us informed of developments.

”This too will pass.”
 

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Discussion Starter #4
Wow, wow, wow. o_O

Have you tried throwing the kitchen sink at it? 😀

While you are clearly not a lazy person, I’m thinking a few $$$ towards a proper scan tool is in order. Actual vs requested rail pressure, for one.

At the risk of insulting your intelligence, all your symptoms, especially the need to keep priming obviously point to a low pressure side fuel delivery problem, but with all the new plumbing, bypassing, lift pump, etc. it would seem you have covered all the bases.

Mark Twain said “It ain’t what you know that gets you in trouble, it’s what you think you know that just ain’t so.”

cant recall where all the LP fittings are, but is there a connection, after the FICM and before the CP3 where you can break in and observe fuel delivery into a container? Also, double check output pressure of the lift pump. I believe that since the CP3 operates as a vacuum pump to pull fuel from the tank, it becomes very unhappy (symptoms, anyone?) if fuel pressure exceeds a few #.

Best wishes and keep us informed of developments.

”This too will pass.”
Yes I feel like I have absolutely everything I can think of. Recently I installed a pipe race valve to eliminate the relief valve even after shimming it. Also replaced the fuel pressure regulator with one from the parts store. While doing this I removed the line that goes to the cp3 and installed an air chuck at the drivers side fuel supply line and pressurized it while spraying soapy water everywhere and did not see a single bubble. I have a buddy that is going to let me swap his ficm just to verify it’s not an electrical problem. I had a buddy with efi live log it and he “said” everything looked good but at this point I would like to verify it myself so I am on the lookout for efi live just to watch what it’s doing. I cannot find a clear answer as to if I can just buy the 500 dollar flashscanv2 from efi live and used it to monitor or do I need to buy the gm tuning add on and extra licenses. Need some assistance. Thanks for actually replying though. Was getting a little worried no one was reading it
 
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