Operation

OPERATION





The Fuel System provides fuel pressure by an external fuel pump mounted under the vehicle near the fuel tank outlet. The Powertrain Control Module (PCM) controls the operation of the fuel system by providing battery voltage to the fuel pump through the fuel pump relay. The PCM requires only three inputs and a ground to operate the fuel pump relay. The three inputs are:

- Ignition Voltage
- Crankshaft Position (CKP) Sensor
- Camshaft Position (CMP) Sensor

The fuel pressure regulator and main fuel filter are combined into a single unit. A strainer inside the fuel tank also provides a means of preliminary filtering of the fuel before it leaves the bottom of the fuel tank.

The fuel tank filler tube assembly, which is permanently fixed to the fuel tank, uses a pressure/vacuum 1/4 turn fuel filler cap.

The evaporation control and Onboard Refueling Vapor Recovery (ORVR) systems should also be considered part of the fuel system. They are designed to reduce the emission of the fuel vapors into the atmosphere.

There are a total of four check-type valves within the fuel tank/fuel filler tube assembly. Two tank vent/rollover valves (1) are inside and near the top of the fuel tank. They provide a means for vapors to vent, yet can close to prevent fuel from entering the evaporative system in the event of a rollover. The fuel tank overfill check valve (5) uses a float and closes the opening at the bottom of the fuel filler tube (3) as the level of the fuel reaches capacity to prevent an overfill condition. The fuel filler tube check valve (4), located below the narrow portion of the tube, has a dual purpose. It also prevents fuel from exiting the fuel tank through the fuel filler tube in the event of a rollover and eliminates fuel from splashing back on the customer during refueling.