No. 14 Poor Fuel Economy: Notes

NO. 14 POOR FUEL ECONOMY REFERENCE CHART (MZI-3.7)

14	POOR FUEL ECONOMY
DESCRIPTION	Fuel economy is unsatisfactory.
POSSIBLE CAUSE	Contaminated air cleaner element Improper ATF level Poor fuel quality Improper coolant level Brake dragging Improper tire pressure PCM DTC is stored Engine cooling system malfunction Weak spark Ignition system malfunction (ignition coil, ignition coil related circuit or spark plug malfunction) Inadequate fuel pressure Intermittent open or short circuit in fuel pump circuit Fuel pump mechanical malfunction Fuel line restriction or clogging Pressure regulator malfunction (built-in fuel pump unit) Improper variable valve timing control system operation Exhaust system clogging Contaminated MAF sensor Improper engine compression PCV valve malfunction Improper valve timing due to jumping out of timing chain WARNING: The following troubleshooting flow chart contains fuel system diagnosis and repair procedures. Read following warnings before servicing fuel system: Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage. Always keep sparks and flames away from fuel. Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injuries or death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete "BEFORE SERVICE PRECAUTION" and "AFTER SERVICE PRECAUTION" described in this service information. (See BEFORE SERVICE PRECAUTION article.) (See AFTER SERVICE PRECAUTION article.) CAUTION: Disconnecting/connecting quick release connector without cleaning it may cause damage to fuel pipe and quick release connector. Always clean quick release connector joint area before disconnecting/connecting, and make sure that it is free of foreign material.

POOR FUEL ECONOMY

DESCRIPTION

Fuel economy is unsatisfactory.

POSSIBLE CAUSE

Contaminated air cleaner element
Improper ATF level
Poor fuel quality
Improper coolant level
Brake dragging
Improper tire pressure
PCM DTC is stored
Engine cooling system malfunction
Weak spark
- Ignition system malfunction (ignition coil, ignition coil related circuit or spark plug malfunction)
Inadequate fuel pressure
- Intermittent open or short circuit in fuel pump circuit
- Fuel pump mechanical malfunction
- Fuel line restriction or clogging
- Pressure regulator malfunction (built-in fuel pump unit)
Improper variable valve timing control system operation
Exhaust system clogging
Contaminated MAF sensor
Improper engine compression
PCV valve malfunction
Improper valve timing due to jumping out of timing chain
WARNING:
- The following troubleshooting flow chart contains fuel system diagnosis and repair procedures. Read following warnings before servicing fuel system:
- Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage. Always keep sparks and flames away from fuel.
- Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injuries or death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete "BEFORE SERVICE PRECAUTION" and "AFTER SERVICE PRECAUTION" described in this service information.
  (See BEFORE SERVICE PRECAUTION article.)
  
  (See AFTER SERVICE PRECAUTION article.)
CAUTION:
- Disconnecting/connecting quick release connector without cleaning it may cause damage to fuel pipe and quick release connector. Always clean quick release connector joint area before disconnecting/connecting, and make sure that it is free of foreign material.