Lift Pump Test

[JPittman]

While driving with the test gauge post filter at W. O. T. saw 5psi. Went to dealer with this info. They tested it and said it's within specs. The way they tested it was post filter and saw 14psi at idle and 10psi W. O. T. but , parked not driving it. Dealer also said something about a vacuum forming at W. O. T. while driving and the pump very likely would drop to 5psi. Two other dealers said the same thing.



I called Cummins. They say the way to test it is pre-filter, cranking no less than 7psi, and no less than 10psi at idle.



Cummins does not have any specs as to what the psi should be at W. O. T. either driving it or parked.



So my questions are, who's right? Who came up with the idea that 5psi while driving at W. O. T. meant a bad lift pump. Was this Star?

 

[chuck3]

When I got my f. p. gauge installed I saw 12 psi at idle and 10 at 65 mph and 4 to 5 wot. I ordered a test gauge from Briar to double check my readings. The test gauge showed about the same + or - 1 psi. I took it in and had a new pump installed and could'nt believe the difference. 16 psi idle 14 at 65 and drops all the way to 12 at wot. Any one below 10 psi at WOT has a bad pump IMO. unless they are BOMBED heavly.

 

[JPittman]

Chuck3



Thank you for the reply. This test was done with Briar's gauge, waiting for my Westach from Geno's.

The above numbers are on a stock truck. Looks like different dealers have different bench marks for testing. Should I go to Utah? Good excuse to go back, we've had some great vacations there.

 

[chuck3]

JPittman, come on any time and I will line you up with a Dealer that will treat you right.