Several weeks ago I had to go get a trailer load of hay about 25 miles away. The FASS pump I installed in 2010 had been working reliably, always between 12 and 15 psi. After we were loaded up we began the haul home and had to climb a grade. The truck has had on and off transmission hunting/TC issues and at first I thought it was pulling that but then I noticed the psi on my gauge fluctuating from 12 to zero to 5 to 12 and back to 5, ping ponging! I began to freak out as we'd lost our VP44 in the past to a dead pump, back before I had a gauge and had replaced the OEM with the FASS. We got over the summit and were coasting down and the psi went back up to 12 or so but would periodically dip. On the flats it bounced around down to terrifying lows and up again, until we got home. Pulled into the yard and parked, shut off the truck after a bit. I figured the FASS was dyng.

The truck sat for several days before I needed to move it, and all I got was clicking. We charged the batteries thinking for some reason they had died. Same result, no chug on bumping the started. LIft pump initially ran and only gave 2-3 psi, and after awhile it wouldn't even run. Figured it had completely died, and that the system had lost prime. I'm hoping my VP44 is ok since the truck got us home and was idling fine when I shut it down.

So, I ordered a RPDRP is which is just the FASS DRP-02 replacement pump itself. Went through the hell of removing the old one, which was pretty dirty and greasy - in fact it's quite dirty in there and I'm wondering if there was a leak going on, especially since I had noticed a loss in fuel economy over the years. Never smelled fuel, though. Anyway....

Today, I finally got the pump installed. Odd thing: I don't remember on the original install them requiring/recommending putting an inline fuel filter before the pump. My inlet Banjo bolt had the little screen inside. I honestly don't remember there being an inline filter included in the kit, but now when you look at the install instructions, there's a filter included.

Anyway, same problem once I got it all good to go. When I bump the starter, there's no chug, and the pump runs briefly but doesn't maintain prime (I can see fuel in the clear inline filter - it fills, and then empties out again when the pump quits running). I cracked cylinders 1, 3 and 4 hoping air would push out and the pump would be able to come up in psi, but again, no chug when I bump the starter and I don't hear the pump running the way it usually would in the past after bumping the starter.

I was hoping that the lack of "chug" when bumping the starter was due to loss of prime/air in the system, but I'm worried something more ominous is going on.

One final note: In trying to suss out the hunting issue, AGAIN, we also were having a parasitic drain on the batteries, and a mechanic friend we hired narrowed found that pulling the I.O.D. fuse fixed the draw problem, but we didn't narrow down what system fed by that fuse was causing the problem...another thread. The I.O.D. fuse was pulled when we made that trip.

I know the lift pump doesn't have a fuse associated with it, but is there a fuse elsewhere that could be related to this issue with starting and running the pump?

Thanks in advance!

 

One thing to try is to measure the voltage at the pump while bumping the starter and after bumping. Let us know what you find.

 

Ok, I haven't gotten that far with testing the voltage at the pump. But I did discover something new....

I swear my mind is slipping, but I forgot to check for codes! So, did that and got PO382, glow plug/heater circuit B. Could this be related to what was ahppening with the fluctuating fuel pressure and now clicks upon bumping the starter, quite lift pump activity, not the usual prolonged strong pump sound.

I'm charging the batteries before further testing to make sure they aren't part of the problem.

 

Glow plugs in a Cummins motor?
Never seen one and I have owned quite a few Cummins trucks.

If you think the grid heater is acting up. Disconnect it and try and start it then.

 

Could be bad batteries, ground issue.

It never hurts to run a small inline filter pre anything that doesn't like dirt. I use the NAPA diesel rated one. It has a metal screen filter, not paper....trust me, get the metal screen one.

Kurt