funcruise

I think I caused my own problem as usual but here goes. I have been adding two cycle oil whenever I fill up, only thing is the fuel gauge hasnt worked for a long while so I fill up at around two or three hundred miles usually. Now I put in a jar of oil [the size of an instant coffee jar] in the tank every time its filled. Well a cuppla weeks ago it was getting hard to start in the cool mornings. First thought came to mind was the lines at the back of the engine to the frame might be sucking air so we changed them both. Next morning, same thing. Through the day it started perfect. Beginning to think maybe a bad line or fitting further back. Didnt have time to look at it for a while. I ran out of two cycle oil so didnt put any in for the next three or four fillups and darned if the truck didnt start better. Now it starts just like a new one again . The only thing I can think of is I was getting too much oil mixed in with the fuel. Oh yes, I changed the fuel filter when it was hard starting but that didnt help either. So what do you think, too much oil mixture or does a Cummins heal itself??

kd460

No, I don't think the oil had anything to do with it. It sounds lik your system is losing prime from somewhere. Other places to check besides the fuel lines you replaced could be the short rubber line between the prefilter and pump, the plastic lines at the fuel tank (connection points can fail), the prefilter itself (probably not but should check/clean the prefilter).

Also the metal lines at the prefilter and injection pump can develop cracks that are hard to find sometimes. I'm not talking about the high pressure injection lines, I'm talking about the metal lines for supply and return.

Finally, the fuel pick up tube in the tank could have a hole in it and the starting problem only shows up when the fuel level is lower than the hole. Good luck chasing it down. KD