Installed new lift pump...Idle pressure 11#...60 mph 7#....Wide open, I let off when pressure gets to 5#...will probably drop to 0#. New pump has 20 miles on it. Did I get a bad pump or is there something else that needs to be checked ? Thanks..

 

Well other then changing your filter if you are measuring post filter I would guess the lift pump. Make sure the electrical connections are good also.

 

Installed a new filter along with the new lift pump. Electrical connections seem ok...pump does the 30 second run when the starter is bumped...pressure takes a nose-dive when the motor is started.

 

you will also want to check your fuel restriction at the inlet to your lift pump. if you have a high restriction , you will see less psi from the lift pump. check it at high idle, you will also want to check for air in the fuel.

 

I purchased one bad pump from Cummins, they stood behind it and gave me a new one.