Tips on replacing Fuel Lift Pump/Cummins 350 ISC?

Well, job done. Wasn't all that bad. Changed both fuel filters right away - installed dry and went through the priming procedure per Cummins instructions. Engine fired right up and purred like a diesel kitten.

DSDP Don wrote:
"mtrumpet".....Typically, when someone does a job like this, they change out other components like the filters. I would only suggest starting the engine first, after replacing the pump and getting the fuel flowing before you change filters and have an issue with dry filters.

Right Don. That is my plan. In fact, my primary fuel filter (I have two) sits about 6 inches in front of the fuel lift pump. Since I have everything opened up and it right there in front of me, it would be foolish on my part not to change the filter(s) right away.

Thanks all.
Fortunately, in my case, I have have good access to my engine from the bedroom. A section of the floor and the bottom of the closet wall comes completely out as one big L shaped piece along side the bed and it gives me complete access to approximately 2/3 of the engine. The Lift Pump sits only about 8" below the floor level right under the access opening. I can kneel or even lay on my stomach (on a nice soft blanket I might add) and the lift pump is right there.

Mine is the original pump and the problem is indeed the gasket leaking. Cummins told me that the gasket for that old series is no longer available, so the only option is to change out the entire unit. The new unit is an identical match for the old unit with regard to size, mounting and porting. Cummins also gave me all of the plugs, o-rings and seals. They said that I could've used the old plugs, but as long as I was replacing with a brand new unit, might as well go with new hardware as well.

I spent the entire evening last night after work cleaning and degreasing the entire area of the engine and compartment around the location of the lift pump to reduce the chance of debris getting into the fuel system once the fuel lines are remove from the old pump. I plan to take new, clean shop towels and wrap them around the ends of the fuel line with a rubber band to help reduce he chance of getting any debris into them. Then, a big part of the job is moving things (cable harnesses, hoses, heat shield from the exhaust piping, etc.) out of the way to give me as much open working space as possible.

The one thing that is currently giving me a problem...There is a plate mounted to the front of the lift pump assembly, that extends off to one side. In that plate, there is a large cable connection/plug which (supposedly) just unscrews from the connection piece mounted to the plate. I'm have a heck of a time getting that large connector unscrewed! I probably don't have to remove/disconnect it, but by doing so, would allow me to move yet another cable out of the way of the lift pump for easier removal. Will try using a small, rubber strap wrench and see if that will help get it unscrewed.

Just for the heck of it, I grabbed a wrench and tried to loosen the mounting bolts of the lift pump. No luck! They're very tight. (Then again, I didn't want to overdo it either and risk breaking a mounting bolt off in the side if the engine block!). I'll soak'em down with some PB Blaster tonight. Hopefully that will help. (It usually does.)

I have a professional mechanic friend coming over in the morning to give me a hand with getting this project wrapped up. I just hope it goes smoothly. We'll see.

Access from above master bed for my 2001 American Coach Tradition. Actually climbed through opening and determined I would have a heckuva time reaching and some things I could not see, so "Cummins Pacific" in Inland Empire replaced mine. Steamed engine and checked for any other items maybe needing to be addressed. No additional items and I had just replaced fuel filter so approximately $795 later, fixed and I left it there overnight. Best money I spent from what I could tell. And yes they used to sell just a gasket, but I could not locate one and just bit the bullet. I do most maintenance and repairs that just come up, but glad I passed on this one! By the way, the lower cost for my motorhome was due to the easy access for the repair technician. Guess he was thinner with longer arms than me:) Good luck!

Happened in my driveway too thank goodness. And as to your:
"Before I get into this, wondering if anyone else here may have replaced yours by yourself? Any tips, advice or anything I should be aware of when removing the old and installing the new pump?"
Have it installed unless you are certain you can reach and don't mind not being able to see everything you will need to work on!

Ivylog wrote:
One of the advantages of this electric lift pump is it circulates the fuel which gets the air out of the system. This pump is why you put the fuel filters on dry with a Cummins engine.
OP, you should be abe to buy the gasket that goes between the lift pump and it's base as it will solve your leaking problem. It will be much easier than replacing the entire unit. Here is a good guide with the part Part Number 4928511 of the larger/older style gasket which your 02 probably has.
*PS, the new pump has more openings than needed so you will need to buy some plugs to fill the extra holes if you cannot buy just the gasket.

Ivylog, this is the way I remember is, too. As I recall the gasket kit is no longer offered and it still won't fix the other leak point which is the electrical connection. New lift pump is different than the old one. Spot on about some plugs. I had mine done for that reason. $932 out the door, parts and labor.

One of the advantages of this electric lift pump is it circulates the fuel which gets the air out of the system. This pump is why you put the fuel filters on dry with a Cummins engine.
OP, you should be abe to buy the gasket that goes between the lift pump and it's base as it will solve your leaking problem. It will be much easier than replacing the entire unit. Here is a good guide with the part Part Number 4928511 of the larger/older style gasket which your 02 probably has.
*PS, the new pump has more openings than needed so you will need to buy some plugs to fill the extra holes if you cannot buy just the gasket.

"mtrumpet".....Typically, when someone does a job like this, they change out other components like the filters. I would only suggest starting the engine first, after replacing the pump and getting the fuel flowing before you change filters and have an issue with dry filters.

I recently replaced mine and supposedly you do not have to remove the base with the five lines going to it... just the pump with the three screws. Did that and when turned on had fuel going everywhere. Had to put the pump back on the new base and change the entire unit. If you have 3/8 bolts holding the electric pump on the base and the new one has 12 point screws you will have to change the entire unit as the opening for the pump on the base are not the same (too big). Before tightening the base to the motor, get all five lines to start as I could not get one line to start without moving the base. Some of the lines you cannot see what you are doing so good luck. I paid $312 for it in MT and no sales tax.

It's not hard if you have good access to it. Just remove the screws (6 MM IIRC) and swap it out.