Engine/Transmission (1998.5 - 2002) Any PN 3990105 pump failures?

[24V-DSL]

Just wondering if any of you have replaced your lift pump with the latest revision, 3990105 (5-01) and experienced failure.



Seems like if this pump has not been superceded for over a year, that maybe this one is finally dependable?



I've been packing the 3990105 around for a long time, and am thinking of installing it as my FP readings are starting to minimally decline after 45K.

 

[_Hyde]

I think this is the one I have...

I'm pretty sure this is the one I put on mine back in August of last year at 33,600 miles. I had no fuel pressure and thought my gauge was bad until I tried another gauge that I had tested on another engine. Its still running strong around 14 psi as of 2 weeks ago which was just under 68,000 miles. YMMV



Darren

 

[24V-DSL]

TTT....

I was hoping for more response, so trying to let this hang around awhile longer.



Maybe this is my hint that I'm on a lot of "ignore posts from this member" ?

 

[Gary - K7GLD]

Let's just hope the lack of response means few failures~



First, not that many trucks out there with the latest pump, and second, maybe they ARE less failure-prone than the previous ones. For my part, I'd like to know at what point in truck production the latest pumps started being installed - mine was built in 01/02 - but I'm not curious enough to remove the stock LP to look for part #'s...



On mine, stock pressure was 16 psi at idle, about 12 WOT - now, with the added pusher, it idles at 25 psi, rarely ever goes below 20 psi - and at the lowest, only drops to about18 psi... That's with a Carter 4600 pusher and readings right at the VP44...



Oddly, the latest stock pumps were displaying an "AA" suffix after the part # - and my new Carter 4600 ALSO had an "A" suffix - makes me wonder if some of the upgrades on the Cummins pumps are being made to the rest of their line as well...

 

[Ramafid]

I have about 25K miles on the 3990105 and no problems so far. I did move it to the frame rail which should help in the long run.

 

[Pit Bull]

Re: TTT....

Originally posted by 24V-DSL

I was hoping for more response, so trying to let this hang around awhile longer.



Maybe this is my hint that I'm on a lot of "ignore posts from this member" ?

I don't think your being ignored. I did not originally respond because the new pump is working great.

 

[_Hyde]

I think the catch phrase here would be that no news is good news.



Darren

 

[AKostman]

My lift pump was replaced at 40k with an AA pump number. i6 psi idle 12 wot. I am very pleased so far.







1998. 5 short box, stock and love it.

 

[A. Brown]

I just repaced my old pump with 45k on it because with the track record of this thing I didn't want to push it too far, plus their fun to change as long as you've got smaller hands. I'm going to watch this latest version carefully to see if reliability has improved. Right now I plan on changing lift pumps every other year as part of regular maintenance

 

[Steve Campbell]

I was Flying blind....

until I installed a fuel pressure guage. The second most important aftermarket guage in my opinion. Tells you when to change filters and lift pumps.

 

[JTBMC]

I lost 2 of the 3990105 pumps in a year about 35,000 miles total on both pumps mounted in the stock location. As long as I dont let the tank drop below 1/2 a tank of fuel the preasures stay up, at a 1/4 tank preasures drop to 12 at Idle and 3 to 4 at WOT. I'm now on my 3rd about 2 months now and preasures are 15# at idle and 7 to 8 at WOT at 160 bucks each I need to relocate it to the rear, and keep the tank topped off. Installing fuel preasure gauges is a must to monitor the preasures.

TJ

 

[Pit Bull]

Originally posted by tjlaffite

I lost 2 of the 3990105 pumps in a year about 35,000 miles total on both pumps mounted in the stock location.

.

TJ

TJ, were these 3990105AA's?

 

[nwinters]

I have had a 3990105 on my truck for about 8 months/15000 mi. It had about 12-13 lbs at idle when I put it in and still does. Crusing at about 1875 rpm I have just over 9psi. Pressure doesen't seem to have changed since the install. I don't know if its a AA pump though, I got it from a Freightliner dealer down the street from me.

I am using an Autometer mechanical fuel pressure gauge, coming off the top of the fuel filter, before filter, with the sender located about 2ft lower than the gauge. Autometer instructions said to locate the sender/gauge level with eachother, but I have mine on a pillar mount so this isn't really possible (woudn't be possible in our trucks unless it was below kick panel probably). How off do you think the gauge could be being mounted above the diaphram sender?

Anyway, I have been really pleased with the performance of this lift pump.

My previous LP killed my VP44, was getting 3psi and dropping to 0 psi when on the highway, just after the gauge install. A few weeks later Hello Comp, byebye VP... .

Nate

 

[MikeR]

I had a 3990105 fail on me with 20k miles of use just like the previous 2 other pumps that failed before with aout 20k miles of use also.

Cummins warrantied the pump and gave me another 3990105 and I currently have 25k miles on it and it hasn't died yet. It is in the stock location. No pusher system.

 

[JTBMC]

Pit Bull,

Both pumps 3990105 were from Cummins, the first was an early model the first batch and it went quick in about 1500 miles the second lasted a bit longer.

The present pump has been on sense April and still holding good preasures.

TJ

 

[Chace TX]

Spoke with the Service Manager today.

Our local delership got a new service manager (they had to, because the old one was costing them sales and running off business). Anyway, I called him this morning to tell him that my fp gauge showed 0-4psi and no more. He said bring it in and lets get a new lift pump on there. Turns out he drives a 2000 Cummins and pulls a trailer every weekend. He said that this new part number has solved their problems. He has not yet seen a lift pump failure with the new number. Hope he is right. He also told me that they do not stock the lift pump. After the vehicle is in the shop they test it and a pump is sent out overnight shipping. Why?

 

[zimman20]

I've got the latest version in with the 'AA' and no problems so far. However, it's only been a couple of thousand miles. Too soon to tell, IMO, we'll see.



zman

 

[fallbrookjeff]

In May I bought a 98. 5 3500 4x4 with 115K, it now has 120K. Last week on my way to Canada, fuel problem in the Redwoods, towed into Eureka. Transfer pump gone, 3 days order time for p/n 5080885AA. Rented Dakota, continued on to Canada, picked up 3500 Saturday, no other problems coming home to San Diego area.



My question: Should I change out my lift pump before any other trips? Should I carry either one or both with me?



The parts guy here in Temecula, says he has sold only 1 lift pump in four years, but sells a transfer pump once every 3 weeks. On this thread, the lift pump seems to be a problem.



I’m confused!



Please enlighten me!!



Thanks in advance.

 

[Shovelhead]

I think the parts guy might be confusing the lift pump for the injection pump.

I think the "transfer pump" is what we refer to as the "lift pump".

 

[Steve St.Laurent]

He was confused. There are only two fuel pumps on our trucks (3 for those of us that have added a pusher pump) - the lift pump (aka transfer pump) and the injection pump. The injection pump is $1300 if you buy it at the right place - $3000 if you buy it from Dodge. Do a search on "lift pump" and be prepared to read for about a week - there's lots of information on here about the lift pump problem. My recommendation to you would be to put an in cab fuel pressure gauge on your truck and then you'll know when it's going bad or has gone bad - at a minimum. There are a number of different things being tried to either replace the stock lift pump with an aftermarket one, move the stock lift pump back to the tank (where it should have been to begin with), or to add a pusher pump back by the tank to help the stock lift pump live. Here's a couple posts I've made with how I've dealt with the lift pump issue (I went through 4 of em in the first 60,000 miles on my truck):



Fuel pressure gauge install - https://www.turbodieselregister.com/forums/showthread.php?s=&threadid=6113



Pusher pump install - https://www.turbodieselregister.com/forums/showthread.php?s=&threadid=19767



P. S. You could have gotten that lift pump from a Cummins distributor for ~$150 and replaced it in 30 minutes and they would have most likely had one in stock. ALWAYS buy engine parts from a Cummins dealer instead of a Dodge dealer - Dodge's prices are 2-3 TIMES what the Cummins dealer charges.