13 RUNNING REPAIRS


The engine won’t start Is there electrical power to the engine?


NO


1) Is the battery isolation switch ‘On’? 2) Check for blown fuse or tripped circuit breaker 3) Is the battery totally discharged? 4) Are the battery terminal leads connected? 5) Is the battery earth lead to the engine block connected and secure?


1) This is a common but surprisingly easy mistake to make. The usual arrangement is to have a single switch in the positive side of the circuit, but many European boats also isolate the negative side. Both must be switched on for the engine to start.


2) Engine control fuses aren’t always easy to find. There may be a small fuse box mounted on the engine block somewhere or – a ridiculous practice on some engines – it could even be wound in beneath the engine wiring loom insulation! You may have to consult the service manual.


3) A battery’s voltage doesn’t have to be zero for it to be useless. A fully charged 12V battery at rest will show around 12.8V. By the time that reading drops to 10.5V it’s effectively 100% flat. If your power management system includes a voltmeter or bar graph type state-of- charge indicator, monitoring the battery condition is very straightforward. If not, you will have to resort to a hydrometer or portable multimeter.


4) Engine starting creates high electrical demands. Any voltage drop due to corroded or loose connections can result in total failure. Check that there’s no corrosion and that the terminal clamps are tight on the posts.


5) The same goes for the cable that goes from the battery negative to the engine block. Vibration can easily loosen the connection, so make sure it’s clean and nip up the securing bolt.


6) Starter solenoids can draw quite a lot of power. To avoid running heavy cables from the starting switch to the solenoid, a secondary switch known as a ‘relay’ is often used. Turning the ignition key activates the relay which, in turn, switches on the power to operate the solenoid. Relays are unserviceable items. If defective they should be replaced.


98 RYA Seamanship for Sea Anglers YES


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