The outboard starts but stalls soon after, when it returns to idle or the choke is pushed in. Narrow down causes such as a closed tank breather, faulty fuel pump or dirty carburettor.

This is the situation where you open the throttle and the revs increase with the engine seeming to run strongly but the boat moves very slowly, or not at all.

Like all internal combustion engines, outboard motors need to be cooled when running. Select this option if your outboard is overheating. You will generally be notified that the engine is overheating by an audible alarm, steam from the telltale or stalling after getting hot.

The engine starts and runs but coughs, splutters or misfires instead of running smoothly and strongly. I show how to test the ignition system, including the spark, high tension leads and coil packs.

When an engine has a vacuum leak extra air is being added after the fuel mixture thereby making the engine run lean.

Four stroke engines require the valve clearance (sometimes called valve lash) to be set correctly to compensate for expansion as the engine warms up.