Possible Cause & Correction

- Check the following items.

• Check that air filter and fuel filter are not plugged. Replace if necessary. Check for incorrect fuel pressure.
• Check for proper operation of thermostatic air cleaner damper door.
• Check for proper float level using external gauge (carbureted).
• Make sure that initial ignition timing is properly set.
• Check for proper operation of TCC or VCC system.
• Check ESC system for excessive retard.
• Check EST system for proper operation.
• Make sure that EGR valve is not open all the time.
• Check for proper operation of EFE valve (carbureted).
• Check exhaust system for restrictions, such as a damaged or collapsed pipe, muffler or catalytic converter. See RESTRICTED EXHAUST SYSTEM CHECK in the BASIC TESTING article in this section.
• Check charging system output. Repair charging system if voltage is less than 9 volts or more than 16 volts.
• Check MAP or pressure sensor output.
• Using Spark Tester (ST-125), check for available secondary voltage.
• Check engine valve timing and compression.
• Check engine for a worn camshaft.