Was looking to buy first 24v, test drove truck and accelerator pedal kept cutting out
 

Alright guys, not new to diesels, not new to cummins, but am new to 24v's.

Guy has a 2001 6spd 24v dually ext cab. Said his fuel pump died twice, and installed a poor mans airdog raptor, called an Airtex. Said normal FP on a 24v is 13, this Airtex runs 15.

First thing I noticed about this "stock" 24v, except the 500hp clutch, is it's BALLSY. I'm talking, accidently burning out in 2nd gear while pulling out of a parkinglot with the road only mildly wet. The cummins I've driven (and the 12v I've owned...) couldn't do a burnout if I held the throttle down and dumped the clutch (an obvious exaggeration..). So boom.. it's quick and it's "stock".

Second thing.

driving down the road, amidst it hauling ass, the power randomly cut out. All of a sudden, I had to keep the pedal to the floor just to maintain speed. I pull into a gas station, and while I'm pulling out, everything is back to normal. Then while driving down the road between 4-6 gears again, the power would randomly cut out and come back.

I get back to the owner, and tell him the truck's power was cutting out. His dad says "oh it did that for you?" and the owner said 'it happens sometimes' and didn't really comment on it. So later that night I txt'd him about the truck. Said I like it, but that thing where the power cuts out is worrysome. He says "oh lol it really did that for you? I thought you were joking". He says that the Airtex he has installed prevents over-revving and overheating of the pump, and if you drive around 2krpms or less, it wont do it.

WTF is going on here?!

I'm thinking either a bad vp or this "airtex" is crapping out or perhaps the DBW pedal is shot??

Its probably a bad vp44 or apps.

Luke

apps? Whats that?

I had an inkling the VP was fried; I even asked the owner how the VP is and he says it's "great".

Also, are 24v's pretty peppy stock?

I think you are correct. sounds like the VP44 or the airtex lift. from past experience with my lift pump, it almost sounds like the airtex isnt working and the VP is acting like a puller. the symptoms you are describing are the same as when my stock lift pump died. I had no knowledge of the fuel pressure issues common to these trucks and I drove it like that until I killed the VP44. thank God It was covered under the extended warranty.

One other thought, is the airtex a unit with an integrated fuel filter? if so could it be clogged and starving the flow of fuel?

good luck, sounds like you have a lead on a nice truck and if you can diagnose before you buy, you may even have a real good bargaining chip when it comes to purchase price.

It's an 01 so just do the key trick to check for codes. it's probably the APPS (accelerator pedal position sensor) but the codes will tell you for sure, 0121 and 0122 are common apps codes, 1688/89 or 0216 would be injection pump codes. Either way, tell him it needs a vp44 and knock 2 grand off his asking price.

So do you think that the IP is in jeapordy? 2 of my buddies think that the IP is def. shot after 2 failed LP's. Is this truck worth picking up? How long would I have to fix it if I were to pick it up and drive it daily?

Is an 'apps' sensor easy and cheap to replace? How do I do the key trick?

Key trick= turn the ignition switch to ON and back to OFF on the 3rd time leave it in the ON position and in the odometer it will read codes if any are present. DO NOT START THE TRUCK during this process. :tu:

APPS is adjustable, the voltage can be either too high or too low, and there is a process to manually adjust it using a multi meter... Start with the key trick and go from there, but I'd try to use the dead pedal/vp44 relationship against the seller, and you'll find out 1 of 2 things... either he doesn't know shit, or he's playing you (which is possible if it does indeed need a vp44.) Just remember the codes I mentioned above and try to hammer him down as much as possible hoping the APPS is the issue, you can fix that in a few minutes and it costs nothing :tu:

Sa-weet! Thanks man:tu:

Good thinking. Will the key trick FOR SURE tell me if the IP is shot? Or is it just a "maybe"?

It should let you know. You can also take it down to your local auto parts store like "Autozone". They can put a reader on it for you, for free.