My 2002 Ram 2500 CTD has no power when it is cold. This has been going on for over a year. We replaced the fuel pump when the problem first started, but got no improvement. Generally, after it warms up it does fine, but it is progressively getting worse, so we took it to a diesel mechanic. He said it needed a lift pump and a transfer pump for $2300. In doing some research it actually sounds like the VP44 and the lift pump are probably bad. Another mechanic is looking at it now, and he says the code it is throwing is for the lift pump, not the VP44 (sorry, don't know the code off hand). My questions: If the lift pump is bad, does that automatically mean the VP44 is bad?, If we replace the lift pump and the VP44 is bad, will it damage the new lift pump?, I have seen you all talk about the "FASS". Is that the lift pump, or a substitute for the stock lift pump? Money is tight, so we need to get this fixed for as little as possible, but we don't want to skimp on the repairs. Just not sure where to start. Any suggestions?

 

it wont hurt a new lift pump if something is wrong with the vp44, but if the lift pump is bad, there is a good chance the vp44 is going to have some problems

 

The VP44 is the injection pump. The lift pump supplies fuel to it. The FASS or Air Dog is a replacement, and much better investment, than another stock lift pump.
The VP44 is lubed and cooled by fuel. When the fuel pressure drops, usually due to a failed lift pump, the VP44 overheats and cooks the electronics inside, and stops working.
Whenever you get it fixed, get a fuel pressure gauge installed ASAP. Monitor the fuel pressure to avoid re-occurance.

 

Thanks for the info. Is it your opinion that the VP44 probably needs replacement as well? Since it seems to do okay after it warms up, I was hoping that meant it was still salvageable.

 

Lift pump and transfer pump is the same thing. Injection pump is the VP44. Without a fuel pressure gauge, it's very difficult to know if the lift pump is bad. The year old "new" pump could have failed already, there were some durability issues. Best bet is to check the fuel pressure.
Since the 24 valve motors are electronic, sometimes sensors will cause odd problems. Check this page for info http://www.dodgeram.org/tech/dsl/maint/3rd_Gen-24v.htm
Look up "cleaning the IAT sensor" That may or may not help you, but it's very inexpensive to try, and it won't hurt anything. Just don't use carb cleaner, use MAP sensor cleaner. Similar item, but OK for the electronic sensors.
Also look up "VP44 reliability issues" for some interesting reading.
Hopefully you can get it fixed without replacing the VP44, but you'll probably need to replace it eventually anyway. I just prefer starting with the inexpensive items.

To answer your original question, no, a bad lift pump does not automatically mean a bad injection pump, but it will lead to it.
And no, a bad injection pump will not harm a new lift pump.