Poor Fuel Economy

SYMPTOM DESCRIPTION:

From an actual road test the measured MPG is noticeably lower than expected. At one time the fuel economy for this vehicle was at a greater average than current measurement.




SYSTEM OR COMPONENT TO CHECK ACTION

FUEL CHECK: - FUEL TYPE
Quality and alcohol content.
- FUEL PRESSURE




IGNITION CHECK: - SPARK PLUGS:
Remove spark plugs, check for wet plugs,
cracks, wear, improper gap, burned electrodes,
or heavy deposits. Replace as necessary.
- IGNITION WIRES
Check for cracking, hardness, and routing.
- SPARK CONTROL operation.
- IGNITION TIMING.



COOLING CHECK: OVERHEATING PROBLEMS.
- Low engine coolant level and leaks.
- Water pump operation, loose belts
- Restricted air flow or coolant
flow through radiator.
- Faulty or incorrect thermostat.
- Incorrect coolant solution - should be a 50/50
mix of anti-freeze (coolant) and water.
- Fan operation (electric or belt driven).



MECHANICAL - ENGINE/TRANSMISSION CHECK: - TRANSMISSION shift pattern.
- TCC OPERATION.
- Speedometer Calibration.
- Dragging Brakes.
- Tire Inflation.