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
^ Refer to Important Preliminary Checks. Testing and Inspection
^ Check air cleaner element (filter) for dirt or being plugged.
^ Visually (physically) check: Vacuum hoses for splits, kinks, and proper connections.
^ Perform On-Board Diagnostic System Check. Testing and Inspection
^ Check owners 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?

^ Suggest owner fill fuel tank and recheck fuel economy.
^ Suggest driver read "Important Facts on Fuel Economy" in Owners Manual.

FUEL SYSTEM
^ CHECK: Fuel type, quality. Refer to System Diagnosis/Fuel Delivery.
^ CHECK: Fuel pressure. Refer to Fuel System Pressure Check/Fuel Delivery.

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

ADDITIONAL CHECKS
^ CHECK: Transmission shift pattern.
^ CHECK: TCC operation - Refer to Transmission Control System. A scan tool should indicate an RPM drop when the TCC is commanded "ON."
^ CHECK: For proper calibration of speedometer.
^ CHECK: For dragging brakes. Refer to Brakes and Traction Control.