# Cummins 5.9 liter lift pump pressure check



## Live Oak (Dec 22, 2003)

I checked my lift pump pressure today to check on the lift pump health and if my fuel filter is needing to be changed. Doesn't seem to be much different from the last time I checked it. It has been very slowly and gradually loosing a small amount of pressure.

When I checked the lift pump pressure for the first time not long after buying the truck; the static idle pressure was 15 psi and it would pull down to 8 WOT. (pulling 5th gear up to about 2,950 rpm) 

The last time I checked it the static idle pressure was 12 psi and it would pull down to 7 psi WOT. (pulling 5th gear up to about 2,950 rpm) 

Today I checked it and static idle pressure was still 12 psi and it would pull down to about 6 psi (it may have been 7 psi as I had to eye the guage at a weird angle. 

The WOT pressure seems a little low but falls within specs. of the dealer's data. The fact that I am cannot pull it down to 0 psi tells me the lift pump more than likely is putting out good volume. 

I still just can't bring myself to fork out $600 for a FASS yet. :tellyou: 

Has anyone else with a Cummins checked their lift pump lately? I would be interested in your results and what you have done to address the lift pump problem. I keep my eye out for a set of used gauges for fuel pressure, egt, and boost pressure but so far the prices on eBay get bid out of sight.


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## Live Oak (Dec 22, 2003)

Am I the only Dodge Cummins pickup owner here? Thought there was a few others? :zoomin:


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## Lamar Holland (Dec 28, 2005)

I have an 01 with the H.O. motor.. Have only 53,000 on it.. I do the LOF change every 5K. Had one problem first two months having the truck, which the lights were on, off, on, off continuosly during night driving. A three way call between Chrysler/Cummins/Dealer and it was determined the heat grids were the problem. The heat grids were disconnected, and it did end the problem. As far as I know, there wasn't a follow up fix for this. Quite a few of the 01 HO trucks had this problem.. Last week's LOF and they replaced a rear U joint. Just broken in now, and I ordered, and got this early in 01. Not many miles considering how long I've had it. I haven't checked pressures or anthing else on this truck.


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## Live Oak (Dec 22, 2003)

They should not have disconnected the heater grids. I think a manifold temp sensor may be bad.


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