How to start a reluctant engine
QThe engine of my Ford Cortina MKII turns on the starter and won’t fire, despite a lot of cranking. The coil gets hot and so do the starter leads. The headlamps stay bright if I turn them on. Should I buy a pocket jump-starter?
Peter Hill, via email
AStop cranking! A small fault that hampers starting can become a whole wonderland of bigger problems once you start cranking the engine for an extended period. It’s best to walk away after a few minutes and return with a battle plan – namely spark, fuel and valves.
A decent spark must be delivered to the right cylinder at the right instant. The correct amount of fuel must be dispensed by the carburettor. Finally, the valves must be opening and closing at the correct time. That’s pretty-much it for most classics. Here’s our standard recipe. Keep a copy of it in your glovebox.
First, inspect the engine bay for loose or broken wires, pipes or linkages. If everything looks OK, remove the ‘King’ HT lead from the distributor cap and hold it close to a patch of bare metal on the engine. Crank the engine and a spark should jump from its end. Now do the same with a spark plug lead (poke something metallic in the end to act as an electrode or fit a spark plug and earth it). If there’s now no spark, the distributor cap or rotor arm is at fault. Clean and inspect for cracks and burning.
Remove the distributor cap and turn the engine until the points are fully open. The gap should be 0.4mm, in most cases. Most problems here are because the ‘heel’ of the points has worn down and the gap has closed up. This would cause the hot coil described in the question, as the coil stays energised for too long.
If there’s no spark at the points, suspect the condenser. If its connections are OK, try fitting another. Also check the wiring inside the distributor. The baseplate should be earthed to the body. The arm of the points and the wire to it should be insulated.
Turn the engine so that its crankshaft timing marks line up. Slacken the distributor pinch bolt and rotate it back and forth a little. Stop and reclamp it at the instant when a spark occurs at the points while turning the body in the opposite direction to the rotation of the rotor arm.
If all that’s fine, move on to the fuel system. Crank the engine for a few seconds, then remove the fuel hose from the carburettor. If it’s not dripping with fuel, the tank is empty, the pump valves are faulty or the fuel line has a hole or restriction.
Remove the air filter. Does the carburettor smell of fuel? Is the venturi wet? This means fuel’s going in. If it’s dripping with fuel, though, it’s flooding – so check the float and needle valve. If everything’s bone dry then the needle valve may be stuck.
If it’s wet, remove the spark plugs and crank the engine with the king HT lead disconnected and the throttle open to expel fuel. Let the plugs dry before refitting. Use the choke sparingly. A quick pump of the throttle sends a jet of fuel into the engine. You can do it once or twice – but no more. Don’t do it if the engine’s hot. Holding the throttle open a set amount, however, is a good way of supplying a weaker mixture to a hot engine. No choke or throttle can work, though it may take a few extra revolutions to catch.
The final thing to check is the is the camshaft timing. A slack timing belt or chain may jump a few teeth, or a previous owner may have set it incorrectly. A rough check is to remove the rocker cover, turn the engine to TDC and make sure both valves of the cylinder to which the rotor arm’s pointing are fully closed. Also check the valve clearances. To confirm cam timing properly, remove the timing chest (OHV) or rocker cover (OHC) and inspect the sprocket/gear timing marks.