01 2500 diesel runs fine most of time under hard accelaration gets dead pedal ,if turn key back just a bit moter does not kill .It will run fine until next key cycle.Does have code p0216 having trouble understanding why turning key back would affect it if pump is bad.thanks for any advice

 

p0216 is a common sign the VP 44 is going ,but you need to check your fuel pressure first low pressure can kick a 216 code also make sure all your electrical connections are clean and tight

 

If you dont have gauges ask Santa for a set. You need to check your fuel pressure. More than likely you lift pump is shot. That being said it probably took out your injection pump(not cheap). So you more than likely need a Fass, Air Dog, ect fuel pump( dont waste your time or money on a stocker it will just fail again, and take another injection pump out), get a big line kit, run it from the the new pump to the filter, from the filter to the injection pump, and then if it still is bad get a new injection pump and you should be good. Mine went under warranty at 40k, the second lift pump lasted 20k more, when I put my gauges on the stock lift pump was putting out 2lbs of pressure. I took it to the dealer they said I had a bad gauge. I put on a Fass pump, big line kit and I got 19 lbs of pressure at idle(so much for what those dealers know) and 13 wide open with my Edge Comp box on level 5. My pressure dropped to 15 at idle but still doesnt go below 12 wide open. My truck has 140k on it now.

Its an expensive fix, but if you do it right you wont have any more problems. This is just what I did other may suggest other options but it worked for me. I had the dealer replace my HO pump and it was free cause it was under warranty. I havent had any problems from it other than when they installed it, they didnt tighten a hose and I had a fuel leak. There is plenty of info on how to do all of this. The hardest being the injection pump. I personally havent done one so I cant say how hard it is. As far as gauges, Fass, and big line kit, that is all pretty straight forward.

Its a crappy OEM design but the aftermarket has fixed it for me. Good luck hope this helps.

 

http://www.bluechipdiesel.com/vp44diagnostichelp.html

Here is some good VP info...