Changing Lift Pump

[C.]

I have my pump off. I have a new pump and harness, but do I need new gaskets (washers) for the banjo bolts? Or should I reassemble with the old gaskets?



Thanks

 

[work2muchplay2little]

I used my old washers without a problem - changed about 2 months ago now.

 

[C.]

thanks work2much, reassembly begins now.

 

[C.]

Ok, new lift pump installed. here is a break down of the PSI before and after.



Before

Idle - 9psi to 9. 5psi

50 mph - 8psi

3psi minimum I remember seeing



After

idle - 14psi

50 mph - 12. 5 - 13psi

3rd gear accelerating to redline - minimum 9psi indicated on gauge



Just thought somebody would like to know.

 

[CumminsAholic]

Wow what a difference... . Guess I'll have to get one as I run 11 idling, 9-10 cruising and 5 wot. Was it the latest rev. pump from Cummins? (The one that Steve posted the #'s for)

Corey

 

[C.]

pump part #3990105

harness part #4025182



The guy working at Cummins had the part # memorized for the pump. I asked him if this was a common problem. He replied no and said they had put a lot of them in school buses.



So sounded to me that they are a common problem.

 

[dresslered]

What specification can I refer to for getting mine replaced under waranttee? Shop Manual claims 10-psi with a maximum drop of 5-psi across the filter. I have the following readings:



idle: 11-psi

normal operating: 6-9-psi

heavy acceleration: 2-psi



I would imagine that the dealer would have a tough time seeing the last pressure with his gauge and he might question the accuracy of my gauge.

 

[FDziurda]

Lift Pump Changeout

Changed mine this morning in my 99.



Very easy job.

Laid blanket over front of truck and did complete job from the top of the motor. Drained some of the fuel from the fuel filter canister, removed lines and two mounting bolts then laid it aside to access lift pump. Used long 3/8' extension and 1/2" "wobbly" socket to remove three lift pump mtg nuts. Comes right out



Pressures Before:

11-12 psi idle (But sometimes as low as 4-5 psi after sitting all night)

8-9 psi cruise

4-5 psi WOT



Pressures after:

15 psi idle

12 cruise

9-10 WOT



Now I have an "Emergency" Spare!



Hope this job goes well for everyone else who plans/needs to do it. Took several weeks to get the pump thru Cummins. They seem to be rather scarce



Frank

 

[MikeR]

CumminsAholic,



I honestly don't think you need to change your lift pump yet if it doesn't drop below 5psi. Even at 5psi means you still have lots of fuel flow.

 

[tjpatte]

Where was the sender mounted for these readings? The reason I'm asking is that with the Westach mounted on the output of the fuel filter of mine with a PM3 I have:



8-9 Psi at idle

6 Psi running at 65

0 Psi at WTO



BTW I'm running 35 inch tires with 3:54 gears and ordered a lift pump today because of my readings and the soon addition of DDIII's and a HX40. I've seemed to avoid most of the problems with the "early" 24 valves (mine built Jan 98) and wanted to see what's up.



Thanks

Tom

San Diego

 

[C.]

I used one of the test ports on top of the filter housing. Also note that my gauge did not use a sending unit.

 

[KEarnest]

Installed my new lift pump yesterday. I also took this opportunity to install Ray's new banjo bolts from Geno's and the big Honkin' air filter. The banjo bolt kit came with 10 new Cummins gaskets.



Cummins pump #3990105

Cummins harness #4025182

Fleetguard air filter #AH19037



I actually ordered part #3990082 from Cummins Atlantic in Greensboro, NC. This is a kit that contains 1 pump #3990105 and 1 harness #4025182. It was $139, the same price as the pump alone.



The only thing that gave me any trouble was when removing the mounting nuts from the original pump, the nuts were pretty well stuck on with locking compound so the studs actually backed out of the pump. It just took a few minutes longer to remove the studs from the pump mounting bracket. I did all the work from the top of the motor.



Basically I drained the fuel filter, removed it, removed the two banjo bolts and in/out fuel lines on top of the fuel filter mount, removed the fuel filter mount, removed banjo bolts and fuel lines from lift pump, disconnected wiring harness and removed lift pump. Installation was opposite of removal with the exception of using the new banjo bolts and gaskets. I torqued the banjo bolts to 18 lb-ft. The last thing was to install the 5th banjo bolt (this was the "shorty" in the kit) to the injection pump side. I primed the fuel filter and off I went. The truck seems incredibly more responsive and powerful now. I will know psi when I my Westach fuel pressure guage comes in. The big Honkin' air filter lowered my cruising EGT's by 100 degrees.



Thanks for all the info, the TDR rules