High fuel consumption

Step 1: Is ignition system in proper condition?

Check battery voltage, ignition distributor, spark plugs, ignition coil, ignition timing, etc.

  • Yes: Go to Step 2
  • No: Repair or replace damaged ignition components

Step 2: Is engine in proper mechanical condition?

Check for mechanical problems: Compression, basic adjustment of valves and engine oil pressure.

  • Yes: Go to Step 3
  • No: Repair or replace damaged components

Step 3: Is the fuel pressure correct?

Test fuel pressure.

  • Yes: Go to Step 4

Step 4: Is the quantity of fuel delivered by the injectors correct?

Remove one valve at a time and inject fuel into a graduate for 30 seconds while engine idles. Compare quantity with that delivered by a known good injector. If quantity deviates from good injector, original valve was defective.

  • Yes: Go to Step 5
  • No: Replace defective injector

Step 5: Is the start valve in proper condition (no leaks)?

  • Yes: Go to Step 6
  • No: Go to Step 5-A

Step 5-A: Is the cold start valve leaking fuel?

Test the start valve for leaks. For this purpose clamp the fuel intake line closed with a clip. Does engine then run evenly?

  • Yes: Replace start valve

Step 6: Is the air flow meter in proper condition?

For testing, see under Engine does not start under Step 9.

  • Yes: Go to Step 7

Step 7: Is composition of exhaust gas (concentration of CO) correct?.

See the Air flow meter test Chart for value.

  • Yes: Go to Step 8
  • No: Adjust CO

Step 8: Is the altitude compensator functioning correctly?

The altitude compensator is installed in some vehicles operated at high altitudes. Check according to Altitude compensator test chart.