Contents: Description ↳ Examination ↳
Description
1. A preheating system is not typically installed, as the engine starts without it at temperatures down to -20°C (-4°F). However, it can be installed on vehicles designed for operation at low temperatures. The system consists of a fuel tank, valve, control unit and electrically heated spark plug. When the engine is started in cold weather, the valve opens, allowing fuel from the tank to reach the spark plug mounted in the intake manifold. An electric element ignites the fuel, which then enters the combustion chamber and helps start the engine.
Examination
2. Locate the glow plug test connector below the battery tray. Connect the connector terminals with a link of insulated wire with two protruding contacts (see Figure 12.2).
Figure 12.2. Pre-heating system test connector terminals.
3. Ask an assistant to turn on the ignition: the heating indicator lamp should light for about 5 seconds and then go out. While it is burning, and for about twenty seconds after that, the spark plug should be working. Make sure of this by carefully touching the warm spot around the candle.
Warning: The spark plug will become very hot if the ignition is not turned off.
4. If the heating system does not work, disconnect the fuel line from the spark plug and place its end in a small container. Disconnect the electrical connector from the spark plug. Connect a voltmeter or 12-volt light bulb between power and ground.
5. Turn the ignition on again. The voltmeter should show battery voltage, or the light should be on, while the heating indicator light is on and for twenty seconds after that. As long as there is voltage, fuel should flow from the pipe.
6. The absence of voltage on the spark plug indicates a fault in the wiring or control unit. If there is voltage, but no fuel is supplied, even though the tank is full, then there is a fault in the wiring to the valve, or in the valve itself.
7. If there is both voltage and fuel supply but the glow plug does not work, remove the glow plug and apply 12V to its electrical terminal. Ground the spark plug body. The heating element inside the spark plug should glow red
Caution: The candle becomes very hot. If the element does not glow, replace the spark plug.
8. Remove the connecting wire from the test connector after completing the test.
(The original source of the publication is on the website: FordBook)