Engine/Transmission (1998.5 - 2002) lift pump #2 dies at 8:15 this morning...

[zman]

Well, my second lift pump bit the dust this morning with only 14,000 miles on the pump. I found out the first one was dead when I installed a fuel pressure gauge with 18,000 miles on the clock. I have no idea how long it had been dead at that point - but I did have to have a new injection pump put in about 1,500 miles ago.



The most recent death came very suddenly. I just happend to look my fuel pressure gauge when I noticed that it was reading very erratic pressure swings from about 6 psi to 16 psi. After a few minutes, it settled at about 2 psi (truck going down the road). At WOT, it was 0 psi. I pulled over to see what was going on and the idle psi was about 5. It figures that I was pulling an 8,000 pound load when it happened, but at least I was only a few miles from home.



When I got home I shut the engine off and bumped the starter to trigger the lift pump. I could hear the pump running, but the pitch of the running pump kept changing. I noticed that as the pitch changed, the pressure changed - so definitely a bad pump vs. a bad gauge or sending unit. Figures it would crap out on a four day weekend when I REALLY need my truck.



Hopefully the dealer can get one by Monday or Tuesday. This is really getting to be a PITA!!!



Steve

 

[Big_Daddy_T]

under warranty

alot of us have spent the 150 bucks for peace of mind. Keep a spare on board with the tools necessary to change it on the road. I see your under warranty but peace of mind is priceless. 150 bucks verses a long hike.

 

[WyoJim]

FUEL FILTER!!

 

[TomGolden]

Re: under warranty

Originally posted by Big_Daddy_T

alot of us have spent the 150 bucks for peace of mind. Keep a spare on board with the tools necessary to change it on the road. I see your under warranty but peace of mind is priceless. 150 bucks verses a long hike.

What he said. I just replaced my first LP at 44K miles, and bought 2 new ones from Cummins myself. Now I have a brand new spare in the tool box.

 

[juicedcummins]

Mine is doing the same thing and has gone as low as 2psi for a few miles with the comp off towing my 2000lb boat.

It's been 2 weeks and it has worked perfect ever since untill today I was reading 16 psi all day @ cruise and 13 @ WOT then all of a sudden it went to 2psi again. After a few miles it did bounce back to 13 but that is low for what I'm used to.

And no it is not fuel filters,they were changed by me 2k ago.

I'm starting to wonder if my overflow valve is sticking?

 

[WyoJim]

juicedcummins... . It don't matter if your fuel filter was changed 5 minutes ago, it can still be the problem. Especially if you have bought fuel since you changed it.

 

[Motorhead]

All I can say is "What a B. S. set up this pump is!"

 

[Bigsaint]

Doesn't it kill ya ??? We have one of the greatest engine designs and they choose to mount an integral part of it's life and blood in a poor location. Why didn't someone at Cummins check to see if the electric lift pump would perform as well as the 12 valves mechanical counterpart did in the same location before they decided to mount it on the block ? Someone correct me if I'm wrong, but isn't the 12v lift pump located right where the 24v pump is on the block ? IMHO, it was a matter of convience to place it there as Cummins tests each motor before crating same and shipping it to DC for the install. It would have taken very little effort for Cummins to have a set up that included positive pressure to the VP44 for testing, leaving DC the task of mounting the lift pump on the frame, back by the fuel tank, where it obviously belongs.



edit... I doubt a clogged FF would produce the erratic swings in FP, that Steve is seeing. Every pump that I watched die, using FP gauges, did so in this manner just before death. They weren't Carter pumps, they were Mallory's, but the erratic psi's were present in each case.



Scott W.

 

[WyoJim]

Bigsaint... . You can doubt a clogged fuel filter will cause wild fuel pressure needle swings all you want. But changing the fuel filter is exaactly what cured my pressure gauge's erratic swings.

 

[zman]

latest part number???

hey guys -



I'm pretty sure my pump is the problem. As I indicated in my initial post, I can hear the pump running and the sound of the running pump was changing pitch. With that change in pitch, I see a change in pressure on the gauge. I'll probably pull the fuel filter out for a quick check, but it has only been in for 1,000 miles. I always buy my fuel at the local co-op, which is THE place to buy diesel fuel around here. They probably sell more diesel fuel than all other places in town combined.



Is 3990105 the newest part number for the lift pump? Is this a Cummins number or a DC number? If it the Cummins number, what is the DC number?



Thanks guys!



Steve

 

[WyoJim]

Steve... I'm not saying it is not the lift pump. It very well could be, but it could also be the sender or the filter.



I too buy my fuel at the local Co-op, Cenex, whose refinery is close by. I filled up at a Cenex Co-op that is located about 10 miles from the refinery and 135 miles from my home. Within 50 miles of the fill up my gauge went nuts, swing to zero then back to 10 then down to run at zero for a ways, then up to 5 to run a while, and over and over. The filter had less than 2000 miles on it, but I still figured it was the filter or the sender or the pump, in that order, because I have been down this problem before. The next day I changed the filter. It still looked the orignal color and there was nothing in the bottom of the bowl. But it solved the problem and that was months ago.

The only thing I can think is that I happened to get fuel right after a tanker put fuel in the station tank and stirred up sediment which I picked up. Oh and this C0-op is a big truck stop also.

 

[Bigsaint]

Okay Jim, if you said it worked for you that's good enough for me. Common sense would indicate that a clogged FF is always clogged and would produce the same low psi's, not erractic pressure. That's what I based my statement on. Guess common sense doesn't always apply, now I've learned something. Thanks



Scott W.

 

[zman]

electrical connection problem???

I'm starting to wonder if I have a bad electrial connection to the lift pump. I needed to drive the truck tonight, on the way I had fuel pressure problems (2-5 psi), but on the way home (about 3 hours later and 25* cooler) I had full pressure (16 psi) the entire trip. I'm going to pull the connector and check for corrosion and add some di-electric grease. I suppose there could be an electrical problem inside the pump itself that could be causing this.



I'm wondering if a bad connection would cause there to still be voltage to the pump, but not enough for it to run full out. As I mentioned above, I can hear distinct changes in the sound of the pump which directly corresponds to changes in the pressure shown on the gauge.



I'll follow up tomorrow...



Steve

 

[juicedcummins]

WyoJim, in this case it is not the filter for two reasons; the fuel comes from the same source{my bulk tank} and it's filterd out off that tank. The other reason is I swithed filters because it was starting to act up.

The bulk tank was filled 2 months ago, so it isn't a fresh dump of fuel causing the prob.

I have since changed my overflow valve and have 16+psi @ idle and 13@ wot comp on 5/5. I'll know by the end of the week if it cured it.



I was called in to help a buddy that runs a shop 2 weeks a go to help fiqure out a 99 24 valve that had just come from cummins.

Cummins said the truck needed a lift pump and changed it. It more than likely did. The truck had the same prob of stumblig and having to be primed if it sat for any length of time. Cummins said that the prob was the VP44 must be bad and it had to be replaced to cure the prob.

It showed up at our door because the owner wasn't satified with that answer.

This is what we did, first we changed the fuel fiter{no diff but thats were you start} Next we stuck in a new overflow valve and that sloved the prob.

This truck came in and the fuel pres was 15. 5 psi @ idle. When you shut the key off it would slam to 0psi. Now after the overflow valve it falls to 0 slowly like the rest of them.

Even Cummins makes mistakes and the owner of this truck is very happy that we saved him a truckload of cash.

 

[WyoJim]

juicedcummins... . Your post about the overflow valve is very informative. I have to file this information away in my little pea brain for future use. I hope it fixed your problem. Thanks again for the enlightenment.

 

[zman]

overflow valve???????

Hey juicedcummins -



My truck has the exact same symptoms that yours has. I was still showing 16 psi with the pump running this morning, but it would slam to 0 psi as soon as the pump shut off (instead of a gradual reduction in pressure like it used to do). Where is the overflow valve, how hard is it to replace and how much is it?? Thanks.



Steve

 

[RCone]

Random Thoughts. I know that a lift pump survey has been done although I don't think I ever saw the final results.



From what I read on this forum, it would appear that most lift pump failures occur on "BOMBED" trucks and there is hardly a member that posts here that hasn't modified the fuel delivery system in some way.



Do we know the percentage of failure on "stock" trucks and I don't mean just those of TDR members, but all trucks sold by DC?



Does "BOMBING" increase the failure rate exponentially?



Respectfully,



Roger

 

[juicedcummins]

zman, I'm not saying it's the cure for all but it is worth a try.

It is located on the VP44 on the return line. It looks like a banjo bolt that has a ball bearing in the middle. The newer ones look a little different but are in the same location. If you are into drilling banjo's this is one you shouldn't do {leave it alone}

As far as the cost it is well under $100 probably like $40. I bought mine about a year ago and was still in the toolbox so I'm not sure on the price.

Very easy to replace.

 

[stseeber]

Lift Pump #

Z-MAN: I just purchased spare pump from cummins west and he required my factory engine # and then said my pump # was 3990105 or (3990082). He said the 5-series #'s were DC. Steve in n/ca. 99 QC, 4WD, 113k still on second pump. Truck completly stock.

 

[zman]

juicedcummins - Thanks for the feedback! Is the valve you described used to regulate the fuel pressure to the vp44 from the lift pump? I wonder if my problem has something to do the new vp44 I had installed a couple of weeks ago. Maybe some crud got in the system somewhere.



Roger - FWIW, my first lift pump died without any modifications to the engine. I have a buddy here in town that also had one die without modifications. Just a crappy design for what the pump actually needs to do...



stseeber - thanks for the part number. I'm gonna have to buy one as a spare so I don't get stranded anywhere.



Steve