Urgent: Returning from Moab... 24v Cummins VP44/P1688

Caver Dave

Caver Dave

Just holdin' it down here in BFV
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Mar 10, 2005
Location
Hooterville (24171)
Truck (99 3500 rower) was slightly down on power rolling in last weekend, so we swapped the fuel filter, installed guage (running 10-12#) and power seemed to come and go. We put a new lift pump (airtex) in yesterday and pressures bumped up a few # (12-14#), but...

Rolling out this AM, was way down on power, so pulled over near CO border... pressure back to 10-12#. Checked codes now P1688 and found vacuum on the tank (stoopid locking cap). After loosening it, pressures back to 12-14# and currently acting like nothing is wrong, but from what I've read, VP44 is pooched... with the only question where/when it does.

We might be able to find one Albuquerque (heard they have a 24/7 Cummins shop there?), but found a few folks that said it may run for months/miles...

Hoping y'all may have some advice? @mysterync

Keep rolling and chance it'll make 1600 more miles or ???
 
Damn Dave, that sucks. My MIL's truck ran for god knows how long on 3 psi before I checked it and changed the lift pump out. It ran 2 more years till the IP crapped out. Seems to me the 10-12 psi wasn't that bad, even though it's not enough. I think your up for a crapshoot. I do hope one of the "experienced guys" gets you an answer. Good Luck!
 
Weird... just rescanned and no codes stored or pending. No power issues either.

Wondering if the stoopid locking cap wasn't venting and marginalizing the pressure/flow?
 
Vent plugged in the tank if it had vacuum. P1688 actually means there is a code on the vp44 computer which doesn't cross over to obd2. It's not terribly hard to change the vp44 out. Is it making boost? 8-10psi is all dodge says the vp44 needs when it is under full load.
 
a_kelley said:
Is it making boost? 8-10psi is all dodge says the vp44 needs when it is under full load.
Click to expand...

Yeap, definitely making boost (though no gauge)...

Just stopped in Bloomfield NM to top off. Added a double dose of DieselKleen & left the cap loose again. Back to normal ATM...
 
justjeepin86 said:
So did you decide to travel on?
Click to expand...
Yes sir. The missing code was a fluke with the ODB2 dongle and reappears on every startup, BUT leaving the fuel cap loose (which I suspect is for a gasser *or* the tank vent full of dobbers) has kept us under full power for 13+ hours yesterday & 5.5 (so far) today... fingers STILL crossed we'll hit Swannanoa by 0200 Tuesday! o_O
 
We'll keep the lights on in Swannanoa for ya' Dave..Bring it On Son..!! :beer:
 
Just an FYI, my 99 3500 had all of those same symptoms of power seeming to come and go (no codes though ever) before the MAP sensor crapped out. It would come and go and confuse the computer. New sensor, never had an issue again.
 
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