my cummins recently developed a cranking problem.
it will crank and run fine with either and i know it is bad for it to use ,so can anyone tell me why all of the sudden it want crank??
i have replaced the lift pump and the crank sensor.
it runs fine once it cranks just dont understand it. ready to shoot it!!

 

fuel filter? check for air in the lines

 

i have primed bleed and changed all i know to do and it still want work.