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.

Construction

The Sequential Multiport Fuel Injection (SFI) system is classified as:

- Multi-point

- Pulse time

- Mass airflow controlled

Operation

Fuel is metered into each intake port in a sequential firing order. Fuel injectors pulse to follow engine firing order in accordance with engine demand. Fuel injectors are mounted on the intake manifold .

An on-board Powertrain Control Module (PCM) :

- Accepts inputs from various electronic engine sensors to compute the required 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 (i.e. from sea level to mountains).

The 4.0L engine uses a closed-type positive crankcase ventilation (PCV) system and an exhaust emission system to control engine emissions 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 in the applicable section of the P