Car Parts and Accessories

1. Initial Car test

The fault can be in either the ignition or fuel system. To determine which, remove the wire from one spark plug and, if its metal terminal is insulated, insert a key or other metal object into the rubber insulation so that it touches the terminal. Hold the wire at the insulated part (well away from the wire terminal to avoid a shock which, with electronic ignition systems could be dangerous), and place it approximately 5 mm away from the engine block.

CAUTION: Moving the wire further away could cause damage to electronic systems.

With the ignition switch on, have a passenger operate the starter. If a blue spark jumps from the wire to the engine block the ignition is in order and you must then look for a fault in the fuel system. To check this refer to 2, the Fuel system test. (If no spark appears, the ignition system is at fault — disregard 2 to 6 and proceed to 7.)

2. Car Fuel system test

After replacing the spark plug wire, remove the carburettor air cleaner and inspect the choke butterfly valve. If the carburettor is fitted with an automatic choke and the engine is cold, the butterfly should be almost closed but, if the engine is warm, it should be nearly or fully open, depending on the temperature of the engine.

If the vehicle has a manually operated choke, check whether the butterfly opens and closes fully when the choke control inside the car is operated. Hold the choke butterfly in the open position (vertical) and, looking down into the carburettor, move the accelerator linkage with a quick pumping action. Petrol should spurt into the carburettor each time the linkage is moved and, if so, the engine probably failed to start because it was flooded.

To start the engine press the accelerator pedal to the floorboard, hold it there and crank the engine until it fires.

If the test does not show petrol is present, proceed to 3.

NOTE: On some types of carburettors, notably the side draught S.U., the choke mechanism is not of the butterfly valve type, nor is it fitted with a pump mechanism, and consequently no petrol will be injected into the carburettor when the linkage is moved.

3. Car Fuel system

As the test has failed to show the presence of petrol in the carburettor, you must determine whether the mechanism in the carburettor or the fuel supply system is at fault. To do this, disconnect one end of the pipe between the petrol pump and carburettor and operate the starter for a few seconds.

If petrol pumps out as the engine is cranked, the supply system is in order and the fault will be found in the carburettor. If, however, no petrol is emitted from the pipe the fuel system is at fault and you should proceed to 5.

WARNING: To minimise the risk of fire when carrying out the above test, the centre wire in the coil should be removed and care taken to ensure that no petrol is squirted onto the starter motor, relays or other electrical equipment or hot exhaust pipes.

NOTE: If the vehicle is fitted with an electrical petrol pump it will not be necessary to operate the starter as the pump should work as soon as the ignition switch is turned on.

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