PossumF250
Registered User
I'm in the middle of replacing the mechanical fuel pump on my 6.9 IDI, and I'd like to know if/why the cam position matters when installing the new pump.
I'm thinking that if I put the new pump in exactly as the old pump was, it should be fine and cam position should be irrelevant as long as the arm/lever is below the cam lobe. However, the instructions that came with the pump and the DieselHub article on IDI fuel pump replacement both state that the tall side of the cam lobe that drives the pump should point upward when the new pump is installed. Mine appears to be pointing downward, and I'd rather not deal with the hassle of getting it turned 180 degrees if I don't need to, but certainly will if it is necessary.
Does the cam position really matter? If it does, why, since the lobe will rotate through all positions with the engine running?
I'm thinking that if I put the new pump in exactly as the old pump was, it should be fine and cam position should be irrelevant as long as the arm/lever is below the cam lobe. However, the instructions that came with the pump and the DieselHub article on IDI fuel pump replacement both state that the tall side of the cam lobe that drives the pump should point upward when the new pump is installed. Mine appears to be pointing downward, and I'd rather not deal with the hassle of getting it turned 180 degrees if I don't need to, but certainly will if it is necessary.
Does the cam position really matter? If it does, why, since the lobe will rotate through all positions with the engine running?