HEUI system components

heui system component

The principal component in the HEUI system, the Electronic Control Module (ECM, 1), is mounted on top of the right front valve cover. The ECM is the “heart” of the engine. The ECM performs engine governing, timing and fuel limiting. It also reads sensors and transmits data to the instrument display system through the CAT Data Link.

The hydraulic supply pump group (2) is mounted in the vee of the engine in the same position as the original fuel pump and governor for the 3408 engine. Flow from this pump supplies the actuating pressure for the injectors. The fuel transfer pump (not visible) is mounted on the rear of the hydraulic pump.

Also visible in this view is the primary speed/timing sensor (3). The primary speed/timing sensor is mounted to the timing gear housing on the right side of the engine. The secondary speed/timing sensor (not visible) is located on the other side of the timing gear housing.

The speed/timing sensors are used to calculate engine speed and crankshaft position for timing purposes. The sensors are self-adjusting, but special precautions are necessary during installation to prevent damage. The sensors maintain a zero clearance with the timing wheel.

secondary speed sensor

The secondary speed/timing sensor (arrow) is mounted to the timing gear housing on the left side of the engine.

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