vp44 Troubleshooting

[A Johnson]

I'm new at this web sight and seem to have trouble posting new topics so please be patient with me.

That said I see alot of questions on the vp44 and ways to t/s it. There are a couple things that have worked for me in the past when I had a no start situation. I hook a combo pressure /vacuum gauge at the vp44 inlet , unplug the lift pump and crank the engine for 20-30 seconds, the vp44 should draw at least 15-20 inches of vacuum. I also had a vp44 throwing 368 faults ( fuel pump could not acheive specefied timing ) I did this test and only pulled seven inches of vacuum. The only symptoms were a check engine light intermittantly. A new vp44 fixed it. The problem with this method of checking the vp44 is that there are no specs for vacuum that it should be able to pull. The theory is that if the internal vane pump cannot pull vacuum then it probably cant produce pressure either. Has anyone out there tried this test, or has anyone figured out how to measure vp44 internal housing pressure. IF my recolection is correct it should be building 300-350 PSI to supply the pumping chamber.

On another note I had a couple buses with ISBs' that had a intermittant hesitation or bucking complaint. The fix for these was to remove the vp44 connector and I found pins 6and7 (power supply and ground) were a little off colored, not burnt black or blue , they just looked a brass color instead of the normal gold.

A Johnson

 

[rubberneck]

Originally posted by A Johnson

On another note I had a couple buses with ISBs' that had a intermittant hesitation or bucking complaint. The fix for these was to remove the vp44 connector and I found pins 6and7 (power supply and ground) were a little off colored, not burnt black or blue , they just looked a brass color instead of the normal gold.

A Johnson

So what do you do with the off colored pins after removing the connector?? did you just "adjust them" for a better contact or replace them??? there are several of us fighting an intermediate shudder, with no trouble codes, and no apparent cure. thanks phil

 

[A Johnson]

Well heres what I did. First I took a small screwdriver and adjusted them so to speak. This cured the problem so I replaced them. Now before everyone jumps off the ship a starts adjusting them, I think a better idea would be to try to make a "gauge" that you judge there size against the other pins. (be careful)

If you do end up replacing them be warned that they are a real bugger to get out. unlike the normal weather pack these seem to have two sets of locking fingers in them. I know the repair ends should be available from your local Cummins dealer.

I'm afraid that the plastic connector wasn't in very good shape when I got done, but the problem did go away.

A Johnson

 

[Diese1nut]

Pumps

A Johnson

I think you have a good suggestion on checking the connector pins. It has been mentioned before that a possible poor ground could have a lot to do with the stumble.

I have also been thinking of wrapping my wiring harness from ecm to pump with aluminum tape to see if there may be some magnetic interferance causing some problems.