If the lift pump runs fine while it's hot wired then the problem is the ECM. You need to have it checked at the dealer, if all goes well they can just re-flash it and all will be fine.

 

Hey guys I think I may be experiencing a similar issue with my lift pump. I just spoke to the local dealer about reflashing my ECM and his response was that as soon as I plug the Edge Chip back into the truck it will override the flash and any updates will be for not. Is this true?

 

not neccesarily

there are actually 2 feeds for the lift pump, 1st is 100% duty cycle for starting
second is 15% for normal operation

the circuit is K135 and the wires are both yellow with white stripe
they come together at splice S160 and it sounds like your 15% duty cycle is falling off
they are in 15 and 35 in pcm connector

this does not eliminate the possibility of a sick pcm

a reflash might fix the issue but I wouldnt hold my breathe
pcm is burnt with the vehicles VIN so i dont think a swap with a used one will work, but you may be able to overwrite the pcm VIN

good luck
scott

 

i had the same dealer and it was a ground wire on pass side battery was broke and touched sometimes and sometimes wouldnt i put a new eyelet on wire to post worked ever since!!!!