Cummins 24v losing power under load, randomly

[Wanttohuntmore]

HI everyone, my dad is missing his second day of elk right now due to an issue with his 2002 Cummins.  It has been looked at by most reputable south sound diesel mechanics and the dodge dealer with no positive results.  They replaced the map? senser yesterday and it still loses power randomly when under a load.  It seems like the fuel pumps are bad but they were tested as fine.  If they were not so spendy we'd just replace them, again.  Any thoughts or suggestions on mechanics?

[Special T]

With a diesel ALWAYS replace the fuel filter when there is a problem FIRST!

Its odd that its sporadic which leans itself to fuel, we do get such crappy fuel tho... Other power robbing issues i had with my 24v were valves not adjusted, most notable pulling a load.

Hopw you guys get it figured out.

[Rick]

Running a tuner? If so pull the tuner and set the truck back to stock. See if it helps.

[baker5150]

I'm willing to bet it's a fuel issue, either pressure drop due to a pump issue or something similar.

[Wanttohuntmore]

Yeah, running a slight Edge tuner, pulled it and still had the issue.  Also new fuel filter didn't remedy it.  Didn't know they adjusted the valves on these.  Course as sporadic as the problem is it doesn't seem like a valve issue though I could be wrong.

[Special T]

Should have the valves adjusted every 30k or so I waited 75k once and couldn't understand why it had so little power...

[Bigtine96]

There is only one reason you will loose power with a 24 valve, and its fuel.. Either you lift pump or your vp44 is acting up.

What fuel pressure are you getting?
Do you have a stock lift pump?
When was the vp44 replaced last?

[birddogdad]

dont know about that old of diesel, however the modern models have a "save mode" that the engine will select if any number of issues (electrical) occur or now DEF empty too. This occurs to protect these motors which will all but run to death if allowed. The result is NO power and now on the '14's some errors result in about 5mph speed limit (effectively idle). If you have ruled out ALL fuel issues and programming curves, i would invesitgate if this was built into your older model diesel programming. Again, just tossing darts here.

loss of power is a relative thing, if what i have described above is happening, there is effectivly NO power. You would think your truck is dying!  I would find it hard to believe valves have anything to do with your issue.

Update: in 2002 the they had a save mode (researched)

[MtnMuley]

Lift pump

[jackelope]

Were the technicians able to reproduce the issue when it was in the shops? If not, then everything they test will likely test good. I agree with a fuel issue...probably the vp44. That's a guess though. Id want to be able to reproduce the problem before replacing parts.
 

[Boogieman509]

Drain the fuel tank and replace with fresh fuel. While your at it change the fuel filter again.

[buglebuster]

Lift pump

[mkcj]

Do you have an aftermarket lift pump "FASS" on the truck? either way it's the VP-44 starting to go! My 98 is on it's 3rd injector pump, put the FASS on when I replaced it the last time, all's good now.

[Special T]

People seem to like higher flow lift pumps that don't sit inside the tank. I know  on my 03 there was a lot of problems with the factory one so I put in a stock in the tank one in.  Keeping the pumps lubricated is pretty important... If you went with an outside the tank pump i would put it as close to the tank as possible. the OEM ones were way up by the steering box.

[Wanttohuntmore]

Thx.  They just replaced the mps twice with two faulty units.  The third should work.  They think the vp44 might be bad from not using additives with the low sulpher fuel.  Glad my gas engine isn't this much of a problem.  Though for hauling a camper that cummins sure is nice.