Cold start problem.

Last year i had a problem with starting my lb7, when the truck was warm it would start and die then it would start and run till the next startup and die again, after paying the dealers a lot of money with a no fix, i contacted kennedy diesel and john suggested i install a lift pump which i did, i installed his single lift pump with wiring harness. And with the truck running i checked all my connections under the truck and found the primer on my cat filter head was not tight from the fuel showing at the primer pump, tightened the primer and all my problems were fixed. Thank you john. When john says a lift pump is needed, do it. Don't hesitate it can save you a bundle in dealer costs.

My new problem started two days ago, went to start my truck after glow plug light turns off. It started and immediately died, tryed to start it again and it started and no problem after that. Yesterday cold engine again and the same problem, started and died. After that it ran all day. This morning before starting the truck i went under the hood and tried to pump the primer on the stock filter but could not move it, it is stuck in the up position. Next i pressed the button on the black box for the lift pump and the red light came on showing it was running, after a few seconds i released the button and tried to start the truck. It started as always.????

I checked codes and found the following.
U1024 unknown
u1026 unknown
h02521 switches sensor indicates rich see p2198

anyone have any ideas, i've gone as far as i can. Thank you

Fuel filler cap. If it doesn't vent properly (or you are using a gasser cap), fuel tank condensed vacuum (develops after hot shut-down) will exploit ANY fuel line leak, even if there's no indication fuel is leaking out. The lift pump will push out the air, but if there's a significant bubble in the line/filter at any time, it will have to push through, often causing a stall. You still have a leak, somewhere. Replace the fuel filler cap, first (make SURE it's "Diesel Fuel Only"). They're relatively cheap, and the problem may be as simple as that.

BTW....
Disregard those codes, for now. They aren't related to your starting issue, and probably nothing more than power-up diagnostics, and typically normal. They should reset themselves as soon as the engine warms up.

Thank you, i have ordered the new gm diesel cap, should be here wednesday, i'll let you know if it helps.

If you have my lift pump and harness the pump will run at key on and do a prime cycle. When there is pressure in the filter head from the lift pump the hand pump will show resistance as it is being forced up.

I might also suggest spinning a factory filter onto the filter head in place of the Cat adapter and test that way..

Kennedy, thank you. I have gone back to the factory filter, it's a pain in the but keeping that gasket on the factory filter , but i've got patients. Can you use your lift pump to prime the filters or do i need to pump the primers all the time when i chabge filters.

My pump should prime the factory filter, BUT you nave to watch your fuel tank level. If you have a low tank and draw fuel out rapidly, you can empty the cup and suck air. If you are above 1/4 tank you should be fine.

Thank you, as always i can always count on an answer. I also replaced the old fuel cap with a new gm cap and i think that fixed my problems.