Fuel System

WARNING: DO NOT SMOKE, CARRY LIGHTED TOBACCO OR OPEN FLAME OF ANY TYPE WHEN WORKING ON OR NEAR ANY FUEL-RELATED COMPONENT. HIGHLY FLAMMABLE MIXTURES ARE ALWAYS PRESENT AND MAY BE IGNITED, RESULTING IN POSSIBLE PERSONAL INJURY.

An on-board vehicle Powertrain Control Module (PCM):
- receives inputs from various electronic engine control sensors to compute the fuel flow rate necessary to maintain a prescribed air/fuel ratio throughout the entire engine operational range.
- outputs a command to the fuel injectors to meter the appropriate quantity of fuel.
- determines and compensates for the age of the vehicle and its uniqueness.
- automatically senses and compensates for changes in altitude (for example, from sea level to mountains).

All engines use a closed-type Positive Crankcase Ventilation (PCV) system and an exhaust emission system to control engine emissions to within government specifications.

To maintain the required exhaust emission levels, the fuel delivery system must be:
- kept in good operating condition.
- adjusted to specifications listed as per the Powertrain Control/Emissions Diagnosis Manual (1) or on the Vehicle Emission Control Information (VECI) decal.

Additional engine performance checks are required to keep the exhaust emissions at the specified minimum pollutant level.

The fuel delivery sub-system consists of:
- a high-pressure in-tank mounted fuel pump.
- a fuel filter/reservoir delivering fuel from the fuel tank through a 20-micron fuel filter to a fuel injection supply manifold.
- the fuel injection supply manifold which incorporates electrically-actuated fuel injectors mounted directly above each of the engine's eight intake ports.
- the fuel injectors which spray a metered quantity of fuel into the intake air stream when energized.

A constant fuel pressure drop is maintained across the fuel injectors by a fuel pressure regulator. The fuel pressure regulator is:
- connected in series with the fuel injectors.
- positioned downstream from fuel injectors. Excess fuel supplied by the fuel pump, but not required by the engine, passes through the fuel pressure regulator and returns to the fuel tank through a fuel return line.