Engine/Transmission (1998.5 - 2002) Won't start

[LDodge]

Installed new lift pump on my 2001 4W. D. 3/4 ton Diesel and it still gives me a code on a Super Chips analizer of P 1688. Engine would not start after getting home from fillup at local diesel stop. I could not hear pump run which I normally can hear. I can't find my code book so any help would be greatly appreciated as to why the big D. does not start. I have bled all the injectors and changed the the water separator filter too.