LB7: Fuel problems

[hammerwood]

I have a 2001 gmc duramax with lb7 was running great until a week ago when i pulled into the driveway and died. It would not start back up. Did some research and i desided the cp3 pump was bad so i replaced it with a new one. Now it still wont start unless i use strating fluid and it will not idle. It also losses prime after i start it. I have checked the lines and they are not clogged, there is not leaks, and no air in lines. My oil pressure gage has also stopped working since i changed the cp3 pump.
Any ideas on what could be wrong?

 

[boominator]

did you change the fuel filter?

 

[hammerwood]

Yes i changed the fuel filter

 

[hammerwood]

And all the rubber fuel lines on the engine

 

[bevi]

maby some air in the lines?

 

[hammerwood]

Started with starting fluid and i keep my foot on gas to keep it running for 30min and it still wont idle. The air should be out of the lines

 

[jraymer]

do you have fuel in the oil?

 

[Texas Chevy]

Fuel filter housing thing where the filter screws on can I bad and won't hold prime u can get a rebuild kit cheap or just a while new one.

 

[hammerwood]

There is no oil n the fuel

 

[rgullett83]

does it pump up with the hand primer?

 

[JustinD]

I'd look at your fuel filter housing, they are a common issue. Also I would change all the rubber lines on the motor, they get pretty dry rotted and cracked..

 

[hammerwood]

Yes it pumps by hand but when i try to start it it loses prime

 

[hammerwood]

I have changed all the rubber lines when i changed the cp3 pump

 

[Sledhead]

I got some BAD fuel a couple weeks ago, truck wouldn't start. Drained the tank and put new filters on now its back to normal (I hope).

 

[hammerwood]

Ok now i have tried pumping the prime and it pumps just fine and pumps up til i cant pump it no more but in 10min of just sitting ( not running not trying to start it ) it loses prime and i cant find where the pressure is going,

 

[blk smoke lb7]

You could have an injector stuck open and you can't maintain the min fuel pressure to keep the ficm working.you can bottle test the returns or a crude test is pull all the glow plugs and pull the inj fuses have some one crank it over with a man on each side of the truck send check to see which cylinders are misting out the glow plug holes.Those would be your injectors that are stuck open.

 

[jonathancasey19]

Not trying to be an asshole but do you have enough fuel in the tank? Reason I ask is because my fuel gauge quit working a long time ago and I keep track of fuel level with my trip odometer. Girlfriend accidently reset it without knowing. Clueless to me, my truck died and had the exact same symptoms. However, there was enough fuel to prime and turn over for a second as well as hearing the lift pump return fuel to the tank. Easy fix.

Where did you get your cp3 from? Is it an LB7 cp3?

 

[hammerwood]

it has no fuel coming from the injection pump and its new it has fuel coming in but none coming out is there anything that can couse it to stop pumping

 

[hammerwood]

i have put injection pump fuel lines filter preasure regulater injectors i got more in parts than i got in the truck so i need some help i dont know what else to check

 

[RENODMAX]

Rebuild the fuel filter head, cheap and easy to rule out. Do you have a way to log fuel rail psi while cranking? So this issue started out of the blue and since it quit running you have put a new cp3, regulator, and injectors in it? Do I have that sequence correct or did it quit running after you put the new injectors in?
And how do you know that there is no fuel coming from the injection pump?