GM Repair Questions? Ask a Mechanic for Answers ASAP
The fuel injection system has a PCM controlled fuel injection pump mounted on top of the engine under the intake manifold. The pump is driven by the camshaft through two gears, one attached to the front of the camshaft and the other attached to the end of the pump shaft. These gears are the same size and have the same number of teeth; therefore, the injection pump shaft turns at the same speed as the camshaft.
The injection pump is a high pressure rotary type that is controlled by the PCM. The injection pump meters, pressurizes, and distributes fuel to the eight injector nozzles by way of eight high pressure lines. An outlet port in the injection pump allows the fuel to enter the fuel return system and then travel back to the fuel tank.