Engine/Transmission (1998.5 - 2002) Lift pump and Inj Pump Question

[JJRSMP12]

After installing a new lift pump last night, I noticed the truck runs better now. But, I also noticed some intermittent missing on the way to work this morning, and when I parked, it missed once. Is this just air still in the system? Or is there something else I should consider. I do not have a fuel pressure guage. I need to get one... Thanks

 

[SCox]

Check your codes. Kind of odd. Changed my lift pump, didn't have any problems. Only time my truck missed is when the vp gave out Mine was my own fault, didn't have a fp guage, added a tst pmax, then added the guage... too late, had been running low pressure with power max and destroyed the vp due to fuel starvation.



Steve

 

[ntillm01]

I've felt a couple of hiccups after changing a lift pump, or fuel filter sometimes. Usually goes away after the first trip down the street. I write it off as air working it's way out. If it keeps up, I'd worry more but at this point I don't think you have a problem.

 

[LStanphill]

How hard is it to change out a lift pump. How Much $$$ & Where do I buy one??

 

[isb360]

I just changed my this past Monday. Latest p/n from Cummins is 3990105. It was $154 + tax. You will also need 4x washers, 2 for the inlet side (one on either side of the banjo) and 2 on the outlet side. Washers come in packages of two and each package was $1. 65.



The hardest part about changing the LP is that no matter how much of a monkey you are, you can only get one arm down to it a time, so you'll need to wrench everything with one hand. I put on a pair of knee pads and climbed up on top of the engine and reached my right arm down to do all the work. Use a 17mm wrench to loosen and remove the banjos, unplug the connector, and remove the nuts on the three studs holding the pump to the bracket. I found that one stud came out from the top, the other two remained on the pump. You will need to reuse the nuts that go on top of the bracket, but the new pump will come with new studs and the bolts under the studs. I noticed that the nuts on top of the bracket were held with red Loctite, although I didn't have any on hand and didn't use any when putting in the new pump.

If the studs stick in the bracket, like mine did, just clamp a pair of vice grips to the stud under the bracket and use a ratchet to back the nut off from the top. It's a PITA, but do-able.



I wrapped a long piece of wire (although I'm sure string would work) around the new LP, that way when I positioned it up under the bracket, I could pull on the string with my left hand and hold it in place while I reached my right hand down to the studs and put the nuts on.



I dropped one of the washers on the inlet side banjo 4 times into the mud, but with some patience I got it done.



My new idle pressure is 12. 5psi, which I think is a bit low, so I am mentally preparing for possibly having to swap it with another one.



Hope this helps.

Tim

 

[JFinke]

ISB360 can you give me a banana or something for being a monkey. I do them from a stool on the fender side and always use both arms to start the first bolt. It's tight but I do walk standing up at the end of the day. Jake

 

[krs]

If it gets too frustrating just drop the starter and do the LP from below. Get the harness from Practical Solutions and move the pump back by the tank where it belongs.

 

[CCOLLAR]

A couple of additional tips:



Place a rag or paper towel underneath the lift pump when disconnecting the banjos. If (and when) you drop the inside sealing washers, they will drop onto the towel.



Loosen or remove the intake line bracket off the LP mount. This makes reinstalling the intake line w/washers a lot easier.



A sturdy stool/bench placed next to the wheel makes accessing the LP from the side of the truck a whole lot easier.



Use dielectric grease on the electrical connections.



A little shop light (I foget what they're called -- a lightbulb with a cage around it) can fit between the engine and wheel well just aft of the intake manifold, affectively lighting the LP. A huge help!



Keep a spare LP around for peace of mind!



Craig

 

[Gary - K7GLD]

It's always a good idea to verify that the 3 mounting/pump plate hold-down bolts are properly snug and properly holding the top pump plate in position - too loose, possible leaks and fuel bypassing around the internal pump rotor = lower than normal PSI - too tight, might cause drag or stall the drive motor...