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: Check for restricted fuel
return line or defective pressure regulator.


COMPUTER INPUTS/OUTPUTS CHECK: ^ ELECTRONIC CONTROL UNIT: Check for
correct control unit and PROM I. D.
^ FUEL INJECTORS: Poor spray pattern,
or sticking.
^ OXYGEN SENSOR:
^ AIR FLOW METER: Sticking flap





IGNITION CHECK: ^ SPARK PLUGS. Remove spark plugs,
check for wet plugs, cracks, wear, improper gap,
burned electrodes, or heavy deposits.
Repair or replace as necessary.
^ IGNITION WIRES for cracking, hardness, and
proper connections.





COOLING CHECK: ^ For obvious over heating problems.
^ AUXILIARY COOLING FAN:
^ FAN CLUTCH: Operation.
^ Low engine coolant level and leaks.
^ WATER PUMP: Loose belts?
^ Restricted air flow to radiator or
restricted coolant flow.
^ THERMOSTAT: Faulty or incorrect.
^ Correct coolant solution - should be a 50/50
mix of anti-freeze (coolant) and water.






MECHANICAL - ENGINE/TRANSMISSION CHECK: ^ Transmission shift pattern.
^ COMPRESSION:
^ Clutch slipping
^ For proper calibration of speedometer.
^ For dragging brakes.
^ For proper tire inflation.