The engine will not turn over :- If the engine does not turn over then the obvious place to start is the battery's state of charge and the condition of the terminals and leads emanating from it. Ensure that the terminal joints are clean and shiny. Both the copper (bright red metal) and the lead (soft grey metal) terminals can be cleaned with a penknife. Ensure all connections are tight. If this is all in order then turn on the headlights to check on the state of charge within the battery. If the battery and the fuses (Fuses melt in the event of an electrical overload and are found within the vehicles fuse box) for the ignition and starter solenoid are good then suspect the starter solenoid itself. (The starter solenoid is a component used to enable the small wire from the ignition switch to electrically close the contacts within the solenoid and thus allow it to pass the many hundreds of Amps that the starter motor requires to rotate the engine). To by-pass the starter solenoid connect one of your jump leads (from the tool kit) to the positive terminal of the battery and to the heavy cable on the starter itself (the one coming from the solenoid). Be very careful to avoid sparks and ensure the vehicle is out of gear. If all is good then suspect the starter motor brushes or windings.
The engine turn over slowly and the battery is good :- Check for heat in the leads and terminals going to the starter. Heat means a resistance to the current and can be caused by frayed wires or corroded terminals. If the heat is generated within the starter motor (it will feel very hot to the touch) then suspect the windings. The engine turns over but will not fire :- First check to see if there is a spark at the sparking plugs. Connect a spare spark plug to one of the spark plug leads and then "ground" this plug to the engine block (by placing the threaded portion of the spark plug onto the engine block). If there is no spark then suspect the fuses that are in line with the wires to the coil and distributor. If there is voltage reaching here (you can find this with a voltmeter or the "light bulb tracer" found on page 15) then suspect the contact breakers within the distributor cap and ensure they have the right gap. (The contact breakers, within the distributor cap, regularly suffer from "pitting" of the contact surfaces and subsequent closure. This affects the ignition timing and can eventually lead to the engine not starting at all). Some vehicles are fitted with electronic ignition which can be mostly discounted in the field as this system is far more reliable. Also inspect the cap inside and out for electrical "tracking". This will show up as crooked lines in the dirt of the cap. Any moisture will also lead the spark to follow the path of least resistance. Dry the components or expel the moisture using WD40 or another water repellent. You can, in an emergency, by-pass the ignition switch by connecting a wire from the positive terminal of the battery directly to the high tension coil's "CB terminal". If the spark is visible on the spare plug it also could be that the plugs within the engine are fouled or have broken down. A weak plug will not spark under the load of compression as the voltage will find some other path to follow. The engine has a good spark but will not fire :- Suspect the fuel flow and quality of the fuel first. Check the tank, pipes from the tank, fuel filter and fuel pump. Lastly inspect the carburettor and air filter. With the air filter removed you will see fuel spray within the carburettor when the throttle is opened. Be careful here in case of a backfire and a flash back. The engine turns over very quickly and smells of gasoline at the exhaust :- In this case the engine is flooded with fuel. Remove the spark plugs and turn the engine over to expel the surplus fuel from within the cylinders. Then add a small amount of engine oil through the spark plug holes. This will boost the compression, which has been reduced by the petrol washing it away from the cylinder bores and piston rings. All of the above are correct but the engine will still not fire :- Check the ignition timing in case it has been altered and also the state of the toothed cam belt. If the toothed cam belt has too much free play it can slip a notch and thus displace the valve timing. Timing belts should always be replaced at the manufacturers specified intervals. More frequently if the vehicle is used in dusty or sandy conditions. Check that the compression is also within manufacturers limits by using a compression gauge in the place of a removed spark plug. If a cylinder is not working :- Pull off the spark plug leads in turn and listen to the engine tone. Be very careful as you could get a very high voltage shock. When a spark plug lead is removed from a bad cylinder the engine will not slow down and there will not be a change in the sound of the engine. Once you have established which is the malfunctioning cylinder, increase the gap between the plug lead and the spark plug. You will here a clicking of the spark jumping the increased gap. This also boosts the spark voltage and can clean a fouled plug (fouled with carbon or oil) in some cases. If this fails then check the plug itself. Oily deposits on the plug indicates a failed plug or worn piston rings or worn valve guides. Black spark plugs are indicative of over fuelling "too rich a fuel / air mixture". White spark plug tips are indicative of over heating and too "weak" a fuel mixture. The correct colour is light brown to grey. It is worth mentioning here that the spark plugs must be of the specified type. All plugs are graduated in a heat range, also some plugs are or the "long reach" type whilst some are "short reach" and should never be mixed up. If the engine is running unevenly and you have eliminated the spark :- This could be the fuel flow through carburettor. One technique for clearing blocked carburettor jets is to rev. the engine up and close your hand over the carburettor briefly. This will draw an excess of fuel through the jets and often clear them. Be careful if you carry out this trick in case you get a flash back (flame back through the carburettor). If this does not clear the fault then a carburettor overhaul and clean is required. Lack of compression :- This is mainly due to a worn out or burnt valves (usually the exhaust). This is one of the reasons why it is of paramount importance to service the vehicle regularly and not forget to adjust the valve clearances at the same time. The other reason for lack of compression is that of worn piston rings or worn cylinder bores. Inspection of the engine oil :- If the engine oil is grey to white in colour then it has been contaminated with water (which has formed an emulsion with the oil). This is most probably due to a failure of the "cylinder head gasket" or the cylinder head itself being cracked. The "cylinder head gasket" is the seal between the engine block (main body of the engine) and the cylinder head (the smaller block on top of the main block that contains the spark plugs, valves etc.). The cylinder head gasket has to seal in the engine compression (and power stroke), plus seal in the cooling water and lubricating oil around the engine, so it is under a great strain and sometimes fails. Lesser amounts of water can build up in the oil due to repeated short distance running and the subsequent condensation. Water in the oil can also be ascertained by lighting the oil at the end of the dip-stick. If water is present then you will hear a crackling sound (e.g. bacon spitting in the pan). Inspection of the exhaust :- If the exhaust is black then this is a sign or over fuelling. If the exhaust is blue then it is a sign of lubrication oil being burnt with the fuel, (coming from worn piston rings, worn cylinder bores or worn valve guides). If the exhaust is very white and steamy then this is a sign of water passing through the engine (probably from the cylinder head gasket). If everything is in correct running order then the exhaust pipe metal itself will be white (for leaded fuel, this is the lead) or brown (for unleaded fuel).
