Join Date: Nov 2008
Location: Salina, Kansas
Feedback Score: 0 reviews
It sounds like you're describing a fuel knock. Look at the top of the injectors for wet spots, that is where the most common place is for air intrusion is. That knock you describe is from the injectors getting a slug of air, or lack of fuel. From there it is anybody's guess. Air comes from many places and will leak in where fuel won't leak out. Usually the bonnets on top of the injectors (which are sealed with O-rings) will start leaking, and the knock is the first sign. After a while, it won't want to start.
1993 F-350 crew cab non-turbo 5 speed transmission
35 years a mechanic on large stationary engines natural gas and diesel fired, and other industrial equipment.