Operation of the 6.9 and 7.3 International-Navistar IDI fuel system
The fuel injection system on the classic 6.9 and 7.3 liter International-Navistar engine used in diesel fords from the 70s to the early nineties is relatively simple, but some confusion still remains about how it functions. The major components of the system are the lift pump, filter head and filter, fuel injection pump, fuel injectors, return system, selector valve, and the fuel tanks.