GM 6.5L V8 – Fuel System – Injection Lines

The high-pressure discharge fittings on the head of the injection pump connect to the injection nozzles with steel lines of equal length and interior volume (see Figure 7-53). The ends of the injection lines have special fittings and nuts.

Intake manifold mounting bolts and studs secure the injection lines, using straps and soft isolators (see Figure 7-54). Each injection line is clamped in three locations to prevent breakage due to vibration from the engine and from injection pressure pulses.

When the engine is not running, fuel is contained in the injection lines. During engine operation, a residual pressure of approximately 500 psi is maintained in each injection line. As injection occurs in each line, a small amount of fuel enters the line, pushing a similar amount into the nozzle at the other end with a pressure wave.

During service, injection lines are serviced by replacement. Diagnosis includes an inspection for tubing and fitting end damage that causes restrictions or leakage.


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