Engine/Transmission (1998.5 - 2002) DC changing their views on lift pump pressure

[Motorhead]

Took the truck into the dealer because the lift pump didn't seem up to pressure. Got it back, without a new lift pump and a work order that said "15psi at idle, 8psi at WOT no load, 7psi at WOT with load. "

They called DC and they said that the #'s are ok... What gives?

I read on the site that 10psi is the lowest that Dodge recommends.

You'll all get a kick out of this... I requested the exaust lock tabs be put on the manafold, I didn't look at them until I got home(dealer is 55 mi away), the mechanic took out the exaust bolts and put the tabs under the bolt heads and twisted them up re tightening the bolts.

Like the old saying goes. . "When you want something done right, you better do it yourself!!" Chris

 

[dresslered]

the mechanic took out the exaust bolts and put the tabs under the bolt heads and twisted

I don't know whether to laugh or cry!



My advise would be to order a lift pump from Cummins and throw your existing one under the rear seat as an emergency spare.

 

[jwilliams3]

Those fuel pressure numbers are fine, actually well within spec.

I recently did a fuel pressure check on a friends new truck and the numbers were almost identical 14-16psi idle, 10psi wot, and 7-8psi with continuous wot.



--Justin

 

[Motorhead]

Yeah David, I think that I will just buy them and install them myself ... . AFTER I re-torque ALL of the manafold bolts.



Thanks Justin, First real #'s that I read for the pump. I have 35,000 mi on it (truck and lift pump) and hearing of ones going dead at half that miles got me worried. Chris

 

[dresslered]

Motorhead-

My lift pump was getting the same results as yours at 20,000 miles. It slowly degraded over the next 10,000 miles until I had 1-psi at WOT. I got worried and swapped it out.

 

[DavidC]

I believe the 10psi is at idle only on the pump side of the filter. I had 11psi on the clean side of the filter and knew that DC would not touch it so I bought a new one from Cummins and changed it out.

 

[jjolin]

DavidC what were your numbers after you replaced your pump?

 

[dresslered]

I'm not DavidC but rather a DavidD. Here were my results:



Original Lift Pump

idle = 9 psi

normal driving = 5-7 psi

WOT = 1 psi



New Lift Pump

idle = 14-15 psi (bingo!)

normal driving = 11-12 psi

WOT = 8 psi

 

[DavidC]

After installing a Westach 0-16 PSI fuel pressure Gauge and new fuel filter and noticing a slight power decrease towing 32' 5th wheel (which started all this).

Original Fuel pump, truck only 33000 miles. All readings post filter.

Idle = 11psi

Cruise = 8-9psi

WOT = 5-6psi



After a visit to Cummins Rocky Mountain in Phoenix (formerly Cummins Southwest).

New pump installed,truck only.

Idle = 14psi

Cruise = 13psi

WOT = 10psi



Will be interesting when the 5th wheel gets connected what it will do now.

Parts breakdown include,

1 each 3990105 pump @ 145. 95

1 each 4025182 wiring harness @ 7. 48

1 each 3935171 sealing washer @ . 96 (Bag contains 4 washers)

1 each CPB discount @ 15. 45

Total cost after taxes = 150. 19



The complete change was done from the top, did not remove anything except the pump assembly. Taking my good old time it took about 1 hour and 30 minutes. Now the idle pressure at 14psi I think coincides with the fuel return pop off that the service manual states is set at 14psi to open. If I am right about this I should not expect to see anything above 14 unless the return valve gets stuck closed or cannot handle the volume supplied to the valve or associated plumbing back to the tank. Am I correct in this ?