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wbhubbert3 · 08-16-2014, 05:44 PM

Purchased our 2003 36FDDS/400ISL in August, 2011.When we started our spring maintenance items in 2012, the “engine” idiot light came on.We added this to our list of items the local Cummins Northwest shop was going to address.It turned out to be a bad lift pump (vehicle always started right up) which was replaced for only $100.00 deductable.Glad we had an extended warranty.

Fast forward to November, 2013 and “engine” idiot light comes on (again, vehicle always starts right up).Back to Cummins Northwest where I’m told the lift pump is again bad.This pump had only lasted 18 months and 5,500 miles.A replacement costs the $100.00 deductable, but no amount of discussion or letters to the home office gave any type of credit to either parts or labor.No explanation as to why this might have happened so soon, either.

Forward to May, 2014 and the snow is gone:I noticed when I turned the ignition key clockwise to accessory (not ignition yet), all the status idiot lights come on and buzzers buzz - both for a few seconds.But, I also get a loud (loud enough to be heard up front) electrical buzzing/pumping noise from the engine compartment.I’ve lifted up the bed and had the DW turn the key and I can definitely hear the noise from the pump and feel the vibration within it.

Back down to Cummins Northwest where they tell me everything reads out normal on the lift pump.

Is this lift pump noise and vibration normal?I just don’t remember it being there previously.I’ve timed it repeatedly, and each time it goes for exactly 60 seconds and then stops.Any past experiences or suggestions out there?

Thank you.

sknight · 08-16-2014, 05:56 PM

If it's the same one that came on my ISB series then yes, it'll wake the dead. I replaced mine with an Airdog direct replacement unit and not only is it silent, it's got great pressure across the RPM range and under full load. Might be worth looking into for yours.

PureFlow AirDogÂ® – Supplier and Manufacturer of Fuel Air Separator Systems and High Performance Lift Pumps

Old Scout · 08-16-2014, 06:57 PM

Yes--on my 03, you can hear the lift pump run with the key in the on position, while standing outside near the engine bay. Only guessing but "normal" run time is probably about 60 seconds, if you dont start the engine. Cant tell you if the lift pump keeps running once the engine starts or if the injection pump takes over that task--interesting question. Nor can I tell you about frequent pump replacement but have heard that ULSD fuel is hard[er] on pumps and gaskets.

Dare I say wax valve but on our 03 the engine fan is controlled by a mechanical wax valve mounted on the radiator. During cool to cold weather when you first get under way, the "check engine" light may come on due to high intake air temps. Once the wax valve is completely open and the engine is approaching ops temps, the light will go off....Assume Cummins is checking codes and is not replacing functioning pumps but this has been my experience with my 03 and the experience of a friend of mine and his 03.....

SteveS · 08-17-2014, 05:15 PM

Sound is normal for mine also but not in the accessory position (which is counter clockwise on mine). It runs for about 60 seconds after the ignition is turned on...this is the pump and it allows fuel to fill up a new fuel filter when it is first installed. You turn the key on and off a couple times after filter replacement to fill it with fuel before cranking the starter. The old diesels didn't do this and you had to fill the filter with fuel before installing them. We don't have to do that anymore.