GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2002 🢒 Safari - 4WD 🢒 Engine 🢒 Engine Electrical 🢒 Poor Fuel Economy

Inspections

Action

DEFINITION: Fuel economy, as measured by an actual road test, is noticeably lower than expected.

Preliminary
    • Refer to Symptoms - Engine Controls .
    • Inspect the air cleaner element, or the filter, for dirt or a restriction. Refer to Air Cleaner Element Replacement .
    • Visually and physically inspect the vacuum hoses for splits, kinks, and proper connections as shown on the Vehicle Emission Control Information label.
    • Inspect the driving habits of the owner for the following items:
       - The A/C is ON full time, or the defroster mode is ON?
       - The tires for being at the incorrect air pressure
       - Excessively heavy loads being carried
       - Aggressive driving habits
    • Suggest to the owner to fill the fuel tank and to recheck the fuel economy.
    • Suggest to the driver to refer to Important Facts on Fuel Economy in the owner manual.

Fuel System
    • Inspect the fuel type, quality, and alcohol content. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Test the fuel pressure. Refer to Fuel System Diagnosis .

Ignition System
    • Inspect the spark plugs. Refer to Spark Plug Inspection .
    • Inspect for an open ignition control (IC) circuit.
    • Inspect the spark plug wires. Refer to Spark Plug Wire Inspection .

Cooling System
    • Inspect the engine coolant level. Refer to Symptoms - Engine Cooling in Engine Cooling.
    • Inspect the engine thermostat for always being open or for the wrong heat range. Refer to Thermostat Diagnosis in Engine Cooling.

Additional
    • Inspect the transmission shift pattern. Refer to Symptoms - Automatic Transmission in Automatic Transmission 4L60-E.
    • Inspect for torque converter clutch (TCC) operation. Refer to Torque Converter Diagnosis in Automatic Transmission.
    • Inspect for proper calibration of the speedometer. Refer to Speedometer and/or Odometer Inaccurate or Inoperative in Instrument, Panel, Gages, and Console.
    • Inspect for dragging brakes. Refer to Symptoms - Hydraulic Brakes in Hydraulic Brakes.