doesn't mean that the lift pump they put on was working very well could of killed the injection pump already. get rid of the stock style lift pump and put on a fass

 

Not my truck and its bone stock, i doubt they want to spend the money for a fass after spending 2k on injection pump and lift pump and paying me to fix a problem that created. I finally figured out that the truck cranks fine if you wait after turning on the key and waiting for the lift pump to run, but it takes 10-15 sec after key on when warm for lift pump to run, could i possibly have an ecm issue causing the lift pump to not run like its supposed to?

 

Are you bumping the key to start or just keying on? Was thread sealant used on the fuel line fittings at the suction side of lift pump

 

when i bump the key the lift pump runs like its supposed to if i just key on it takes 10-15 seconds to run, all this while engine warm, it has no issue starting cold. the suction side fittings are all banjo bolts and seals but new seals were used.

 

We had a customer install a lift pump a few months back and he didn't have seals so he found it resourceful to use thread sealant...
The next step would be to pressurize the tank with just a touch of shop air. Any suction side leaks will show up that way.
I would also use a scan tool and verify if its calling for lift pump at key on, and the pump is on when its called for. I hate to say what is normal operation, we have had issues where the pcm "pulses" the pump for 10 seconds and cuts off, yet after the truck starts, the pump operates normally. Graphing of the lift pump circuit showed the pulses and the computer showed it as desired.

 

Thanks a lot mysterync, are you associated with L&N Performance? because the truck in my signature i actually bought from a guy in boone and it had a L&N Performance sticker on the tailgate, off topic but just wandering. I will try to get ahold of a scan tool or drive it to work (Cummins Atlantic, Inc Charlotte, NC) and see if i can monitor the pump commanded versus the actual pump and let you know what i find.

 

Yep that's us. It looks like a truck we had some dealings with. Pm me the previous owners name and I'll let you know.

 

I dont remember the guys name, but the truck has 370 marine injectors that were installed when i bought it, it didnt have the stacks or the tow mirrors on it when i bought it though. could you do any thing with the VIN?

 

I think it was a guy named Jessie I know.

 

well i found out that the pump runs everytime the ecm commands it to, but i still dont understand why my pressure is dropping so fast when the engine is cut off. should these stock systems hold residual pressure for a certain amount of time?