Dodge Cummins Diesel Forum banner

1 - 15 of 15 Posts

·
Registered
Joined
·
13 Posts
Discussion Starter #1
Ok. Customer brought their truck to me for a different reason. I fixed that. He left and came back an hour later and said its surging really bad in drive. But idles perfect in park and even revved it to 2200 rpms in park and ran great.

Right off the bat I checked fuel pressure. He was running 5 psi at idle...awesome fried pump.... I asked him if he changed the fuel filter he said no.... never. I replaced fuel filter and it was black. Bled system and fuel pressure is at 12-14 psi at idle. Drove down the street and it dropped to 0 psi under half throttle and then started surging..bouncing around 500 rpms. He had me install a air dog on truck and pressure is perfect and stays very consistant at 14 psi. Truck still surges and I only get the code p1689.... now he tells me the LP was replaced once. I think he fried the vp44....

Ok so I start doing diagnostic on vp44 issue. I checked all wires from the vp44 to ecm. They all ohm out great. Checked ground by starter and that's fine. Plugged harness back into ecm and started probing and checking power on wires and grounds and so on. Pins all look great. Replaced the fuel pump relay and still doing the same thing. I'm pretty confident that the vp44 is toast on this truck. He ran it low on fuel for a long time.... he also stated the truck sat for a year.

What do you guys think? I'm pretty confident on the vp44 being toast.
 

·
Registered
Joined
·
19,141 Posts
Maybe this will help.
What did you work on?
Maybe bad lift pump has already damaged the VP. Mechanical timing failure does not always code until it dies.

 

·
Registered
Joined
·
13 Posts
Discussion Starter #3 (Edited)
I replaced alt since it wasnt charging and I fixed his battery terminals on his batterys and cleaned up some horrible wiring.

Chewed wires on the oil pressure sensor. Checked all wires from there to see if I can find more chewed wires but I didnt. Fixed his wiring for the fuel pressure sensor and cleaned up his edge tuner wires. I disconnected the tuner from the truck completely hoping it was that but no luck.
 

·
Registered
Joined
·
19,141 Posts
Keep going, under PDC, all harness, and under dash. New alternators need to be checked for high ac out of the box, need under .05vac.

"Drove down the street and it dropped to 0 psi under half throttle and then started surging..bouncing around 500 rpms. He had me install a air dog on truck and pressure is perfect and stays very consistant at 14 psi. Truck still surges and I only get the code p1689.... now he tells me the LP was replaced once. I think he fried the vp44.... " I tend to agree due to long term LP issues and symptoms are consistant, especially if it will not go over 1500-2000 rpm, should go to at lleast 3400. Just have not got internal failure code yet.
 

·
Registered
Joined
·
13 Posts
Discussion Starter #5
I'll check ac output tonight.

I power braked it last night and smashed the pedal to floor it made it 3200 rpms and then totally shut down.
 

·
Registered
Joined
·
19,141 Posts
It shut down . or you shut it down? If you did that and let off sharply you may have created an over boost shut down. After it sits a bit, and 5-10 star attempts it should start if that is what happened. The VP can cavitate and get an airlock in it and cranking will self bleed it out.
 

·
Registered
Joined
·
13 Posts
Discussion Starter #8
Well.... checked AC at idle. .050-.057
AC at 1500 rpms .059-.069

Pulling alternator off and replacing unit.
 

·
Registered
Joined
·
13 Posts
Discussion Starter #9
Removed alt belt and jumped truck with a charger to keep voltage up. Still same issue. Here is the link of a video. I'm 95% sure its vp44.

First part of video I'm at quarter throttle and at end of video I slowly pushed pedal to floor

 

·
Registered
Joined
·
19,141 Posts
If that is not you letting off, I think you are right about VP44.
 

·
Registered
Joined
·
19,141 Posts
You can spend a grand or three grand.
 

·
Registered
Joined
·
13 Posts
Discussion Starter #13
I'm ordering through a local oreillys. With my commercial discount I can get a standard vp44 for $1300 with a lifetime warranty.
 

·
Registered
Joined
·
19,141 Posts
That is OK since it is lifetime. Do you hve to give them your old one as a core?
 

·
Registered
Joined
·
13 Posts
Discussion Starter #15
Yes. Core is $400

$1300 is with core exchange. I'm really good friends with the manager since I do work for him so alot of stuff slides.
 
1 - 15 of 15 Posts
Top