LB7: Need HELP

[05chevy]

I have been working on a guys truck 02 145k on it. Truck would run fine shut it off then wouldnt start after it was warm. Let sit for hour start up and run fine again. Then truck wouldnt start at all. We replaced Injectors because they have never been replaced. Figure they were returning to much fuel to thw tank not building enough pressure to start. Well replaced the injectors. Started right up run good took for a drive and now wont start again. What could be wrong with it. Has anyone had problems with the ficm getting hot and not letting the truck start? Any help will be greatly appreciated

 

[Bustedknuckles]

Try putting a bag of ice on the ficm and let it sit for a few minutes and retry it. I've heard of that being done on 6.5s.

 

[05chevy]

Anyone?

 

[blk smoke lb7]

sounds like the rubber part of the fuel line might have a pin hole or a crack on the inside it might balloning on the inside or colapsing or posible crap in the tank around the suction filter,when it wont start have you checked to see if the primer is hard?

 

[Mpsoldier]

check the fuel prime i have it before were i would loose prime just enough for a no start after it sat for a while pump it twice start back up no problems.:thumb:

 

[05chevy]

You can prime it but the primer ball will never get hard to push always kind of soft.

 

[blk smoke lb7]

You can prime it but the primer ball will never get hard to push always kind of soft.

Even after is sits and its cold? I would think it would have to pump up at that point.Well it cant suck from the tank or its by passing to the tank.If he has a lift pump hook up a 30 psi fuel presure gauge if no lift pump,hook up a vacum gauge to the test port next to the altenator and see what you have for vacume.I think Henry has the specs posted uder the Creatures area.

You could try this after you run it and it wont start unhook the return line next to the glow plug controler and put a catch bottle there and see if you have presure or any fuel at all if you have a decent return the line from the tank should be ok but if no fuel you have a blockage or something in the tank but the only way to be sure is botttle test.

 

[TheBac]

There's probably an air leak in the fuel line or the filter head somewhere.

 

[Mpsoldier]

x2 on air leak on fuel line or filter head i had it do it to me several times after my rebuild then it stopped oneday

 

[Bustedknuckles]

I have a filter head rebuild kit laying in my toolbox I bought and then decided to delete the filter head. PM me if you want it.

 

[05chevy]

I went to try it this morning primed it the prime ball got hard and it started to it for a drive everything up to temp. Come back shit it off. Wouldnt start. U can reprime it and it will start some times run for a while. Some time it will just shut off after and minute or 2. Put a different filter head on it from another truck that ran fine still does the same thing. I can not see any leaks from the fuel lines nor anyplace else. Ill have to try the bottle test.

 

[blk smoke lb7]

Should be interesting either not much fuel or the bottle is going to fill pretty fast

 

[05chevy]

I did the bottle test. I used a regular gator aid bottle. And i got 2" on fuel in 1 minute. I dont know what is to much so hopefully you guys can help me out. Also when the primer started to get tight fuel started to come out the return line. Not a bunch but a nice lil stream

 

[05chevy]

Any suggestions?

 

[TheBac]

Well, if its not fuel related, then start checking electronics. Start at the relays in the fuse box. Could be one is bad when it gets warm. Ive got nothing else. Sorry.

 

[Dirtymaxx03]

2'' of fuel within a minute? im not positive but im pretty sure its returning way to much?

 

[Chevy1925]

I did the bottle test. I used a regular gator aid bottle. And i got 2" on fuel in 1 minute. I dont know what is to much so hopefully you guys can help me out. Also when the primer started to get tight fuel started to come out the return line. Not a bunch but a nice lil stream

ok lets clear up a few things here. you bottle tested what? the FPR? or did you pull the return line off the CP3 and stick it in the bottle and crank/run the truck? what does efi show for fuel rail pressure when your cranking hot? does the pressure shoot straight to 4-5k? or slowly build?

 

[05chevy]

I bottle tested the return line that is on the driver side of the motor right above the feed line from the tank. I can prime the system and it will start and run fine shut it off and you have to reprime it. I will have to find another laptop because mine took a sh!t on me. Then ill check the rail pressure when starting

 

[blk smoke lb7]

You will have to search out the #s for how long to crank and how many mili liters i believe it is.I do not have the info,it should be in Henrys gm specs somewhere.

 

[05chevy]

Ok i pulled a vacum test on the return side of the fuel system. I blocked of the fuel line coming from the filter to the cp3 and pulled vacuum out of the return line going to the tank. I pulled 25psi and it stayed the for 15 minutes. I also primed the fuel filter while the line to the cp3 was blocked off held prime for 15 minutes. As soon as i put everything back to normal. Once u prime the truck it starts. You can prime the system and with in 15 seconds it loses prime. I know if the fpr is bad with will lope but could the fpr be stuck open just a hair that its leaking prime? Or os there a check valve in the cp3 that is bad. Also tested rail pressure with efi live. When primed as soon as it hit 2500psi it starts and it does that right away. Shut off and rail pressure drops to 1200 psi and stays there. Crank the motor to start with out re-priming and the rail pressure drops to 200psi. All injectors have been replaced and balance rates are all 0.** except one is -1.25. My guess would be something in the cp3 but could it just be the fpr? Or am i leaving something out of the equation? Any ideas or suggestion i would appreciate it. Thanks for the help