Poor Fuel Economy

Definition: Fuel economy, as measured by an actual road test, is noticeably lower than expected. Also, fuel economy is noticeably lower than it was on this car at one time, as previously shown by an actual road test.


PRELIMINARY CHECKS

^ Perform the careful visual checks as described at start of "Symptoms,".

^ Visually (physically) check: Vacuum hoses for splits, kinks, and proper connections as shown on "Vehicle Emission Control Information" label.

^ Check owner's driving habits.

- Is A/C "ON" full time (Defroster mode "ON")?

- Are tires at correct pressure?

- Are excessively heavy loads being carried?

- Is acceleration too much, too often?

^ Check air cleaner filter for dirty or being plugged.


IGNITION SYSTEM

^ CHECK: Ignition timing. Refer to "Vehicle Emission Control Information" label.

^ CHECK: Spark plugs. Remove spark plugs, check for wet plugs, cracks, wear, improper gap, burned electrodes, or heavy deposits. Repair or replace as necessary.


COOLING SYSTEM

^ CHECK: Engine coolant level.

^ CHECK: Engine thermostat for faulty part (always open) or for wrong heat range. Refer to Cooling System.

ENGINE MECHANICAL

^ CHECK: Compression.


ADDITION CHECKS

^ CHECK: TCC operation (A/T). Use CHART C-8. A "Scan tool" should indicate a revolution per minute drop, when the TCC is commanded "ON".

^ CHECK: For exhaust system restriction.

^ CHECK: For proper calibration of speedometer.

^ CHECK: Induction system and crankcase for air leaks.

^ CHECK: Fuel injectors are correct for the vehicle.