Poor Fuel Economy

POOR FUEL ECONOMY

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



PRELIMINARY CHECKS


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

^ Check air cleaner element (filter) for dirt or being plugged.

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

^ Perform "On-Board Diagnostic System Check."

^ 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?


NOTICE: Suggest owner fill fuel tank and recheck fuel economy. Suggest driver read "Important Facts on Fuel Economy" in Owner's Manual.



ADDITIONAL CHECKS


^ CHECK: TCC operation - Use CHART C-8. A scan tool should indicate an rpm drop when the TCC is commanded "ON."

^ CHECK: For proper calibration of speedometer.

^ CHECK: For dragging brakes.



FUEL SYSTEM


^ CHECK: Fuel pressure. Use CHART A-7.



IGNITION SYSTEM


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

^ CHECK: Ignition wires for cracking, hardness, and proper connections.

^ CHECK: Proper operation of IC system. Refer to "Distributor Ignition (DI)".

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



COOLING SYSTEM


^ CHECK: Engine coolant level.

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