Engine/Transmission (1994 - 1998) New Lift Pump and 370s in

[bighammer]

I got the new pump yesterday and worked a bit on getting the old one out and began to install the new one. This morning I made a lot of headway, (wife thought it was going to be all day and made other plans) and I already smelled like fuel, so I put in the 370s.



WOW, what a blast Oo. Oo. My Con O holds much better than my tires Temps don't seem bad, but my test drive was short. No stumble as far as could tell either. Not sure if it's the injectors or the pump, but I would swear the truck is quieter.



Out of curiosity, I pulled the old pump apart. Inside I found some small bits of metal. One check valve was blown apart and sort of cocked sideways in the opening.

 

[bighammer]

I noticed the new pump has a larger plunger for the manual pumping. Anybody else replaced theirs? It seems much more effective.

 

[T. Baker]

How many miles did you get out of the original lift pump? When it failed did the truck quit or did it happen at home? I have been thinking about getting a electric just incase my lift pump were to fail I could get home on the electric.

 

[bighammer]

About 120,000 miles.



I heard an occasional tapping sound like a sloppy valve lifter but I ddin't know what it was. It would sort of come and go, but I could not pin it down. I thought it was fuel supply somehow, but I wasn't sure. I sort of thought it was just me so I didn't bring it up in WI at the Kenosha get together. At one point backing out of John's drive, it was bad enough that I got out of the truck and walked around while it idled. I didn't know what it was, and didn't want to dig into there, so I ignored it and hoped it would go away. It did for a bit. I knew I needed to change my fuel filter and I had thought about checking the strainer screen. Brought the parts to do it there, but got into some awesome chili, beer, and conversation with some great guys, (OK, I'm stretching ) and just blew off the work I had planned. I guess I was affraid of being paranoid arround new friends.



Everything was fine until I changed the filter. (at home) I pumped that GD. plunger forever. Stupid me kept thinking... Well it took a while last time, I must be close and kept going.



Finally gave up and reallized it wasn't moving any fuel.

 

[Cooker]

I've been chasing an intermittent ticking noise for 30k. I gave up on it sometime back. Perhaps my suspecions of a bad lift pump may be accurate

 

[Dieselnerd]

Mine went bad at about 70,000 miles. It worked fine after you got it started but lost prime in a few hours of standing. The check valves are about the only thing that goes bad in them. It's a piston pump and the piston looks like it would last the life of the engine. The part of the pump that has the rubber primer button on it is a separate little pump with a plastic piston that is only used during the priming function. New style pump from Cummins is larger than the original. It's been upgraded several times over the years. Latest version is P/N 3936316