GM 6.5L V8 – Fuel System – Fuel Return System

The fuel return system has several different sizes and types of hoses and pipes connected to each other and sealed with compression-type clamps. The injection pump housing pressure regulator connects to the return system, using a hose and two clamps (see Figure 7-57, view A).

The nozzles for each cylinder head use a system of short lengths of small diameter hose to connect to a metal pipe at the front (see Figure 7-57, views B and C). The rear fittings of the nozzles for cylinders #7 or #8 have caps and clamps.

The return hoses for cylinders #1 and #2 connect to a center pipe (see Figure 7-58, view A). The injection pump fuel return hose also connects to the center pipe, and it connects with a hose to a pipe mounted under the right underside of the intake manifold (see Figure 7-58, view B).

At the rear of the engine, the return system pipe under the intake manifold connects to a series of hoses and pipes that send fuel back to the fuel tank (see Figure 7-58, view C).

During diagnosis of the injection pump, the return system is checked for restrictions. Any blockage in the path of fuel leaving the injection pump will greatly affect the performance of the engine.


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