02 5.9 HELPPPP
 

So I have a 2002 2500 with a 5.9 5 speed.
yesterday after work I was running roughly 2k rpm doing 45 or so in 5th. The engine died and I was coasting while not being able to start it backup with either the key or roll start. I came to a stop and cycled the keys two times. The truck would crank and crank but would not turn over.
The engine light did come on as well.
truck is throwing the code P1668.
I have researched quite a bit and almost everything is pointing to a bad injection pump. My main question is could it be just a bad lift pump? Or had my lift pump burnt out weeks ago and my injection pump finally gave out.
there are no modifications to the truck. I bought it exactly a week ago and have put less than 500 miles on it. Truck was running amazing up until this point.
thanks for any advice
-nick

First thing to do, is to check fuel pressure. That will answer the lift pump issue.

If the lift pump is bad or weak, then it puts additional strain on the injection pump. These trucks do not require a lift pump to fire up and drive. However, with a bad/weak lift pump the VP44 will wear at a dramatically increased rate. The additional fuel supplied by the lift pump is what cools the injection pump. The truck can run and drive with a bad lift pump and then take out the injection pump without warning.

P1668 is usually linked to an injection internal pump controller failure.