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2001 ram 3500 4x4 dually 5.9l
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Discussion Starter · #1 ·
I’m not very knowledgeable with cummins, just bought my first 24v.
I was driving home yesterday and went to leave a light and when I hit about 1500 rpm the pedal went dead. I pumped it a little and it came right back. Then about 10 minutes later I was driving slow through a neighborhood and the rpm stuck at 1300 and wouldn’t go down after I let of the gas pedal and I kept creeping along. Then the truck died I pulled over and it would start. I cycled the key a few times and still nothing. Waited about 2 minutes and it started right up. The check engine light came on and when I got home I check and got
P 0123
P 1693
P 1694
P 1691
P 1689

My best guess is my injection pump but just wanted to see what others thought.
 

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Pretty good guess. 1689 pretty much confirms that. But there is two things you can do before VP replacement. 123 code does not usually come up with the VP codes. So do this: Start with checking and cleaning to perfect connection and corrosion free battery cables and terminals. Shiny metal lead connections. The other is check the APPS output pin #3 in the plug voltage with the key ON, running or not. It should be around .5v at idle and smoothly graduate to about 3.8v at WOT without skipping or spiking. If those are OK proceed to shop for a VP. Should be around a $1000, not much over that. You can do in half a day with a few tools.
 

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Registered
2001 ram 3500 4x4 dually 5.9l
Joined
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2 Posts
Discussion Starter · #3 ·
Pretty good guess. 1689 pretty much confirms that. But there is two things you can do before VP replacement. 123 code does not usually come up with the VP codes. So do this: Start with checking and cleaning to perfect connection and corrosion free battery cables and terminals. Shiny metal lead connections. The other is check the APPS output pin #3 in the plug voltage with the key ON, running or not. It should be around .5v at idle and smoothly graduate to about 3.8v at WOT without skipping or spiking. If those are OK proceed to shop for a VP. Should be around a $1000, not much over that. You can do in half a day with a few tools.
Awesome thank you I’ll check that. If that voltage does pass the 3.8v or Spike. Will I need a new APPS as well?
 

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A little over that is fine, What I mean by spike or skip is if you are smoothly accelerating the apps and say you are moving past 1.5v adn all of a sudden it stays there or jumps further than it should for the input you give it is what I mean by skipping or spiking.
Apps are pretty simple and do not go bad near as often as thought.

Bad lift pumps with low pressure are the most common cause of mechanical failure of a VP. Fuel pressure must be checked for every VP failure
 
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