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 What is a trigger/timerbase?
You may have heard both of these terms used when it comes to outboard boat motor ignition systems. Although they look a little different, they are essentially the same thing. The term "trigger" originated from Mercury Marine, the term "timebase" originated from Outboard Marine Corp.(Johnson/Evinrude). This component, located under the flywheel, is pretty simplified and operates on an outboard boat motor much like a distributor does on an automotive application. The flywheel has a magnet located on the center hub. The trigger/timerbase has a series of sensors that detect the magnet on the flywheel as the motor turns. When the flywheel magnet passes by the sensors, the sensors send a signal to the power pack/switchbox telling it to release energy and which cylinder to release the energy to. The trigger/timerbase controls the timing on an outboard boat motor using mechanical advance. As you push the throttle handle forward, the throttle linkage on the motor rotates the trigger/timerbase which advances the timing appropriately to match the rising rpm. If the timing did not advance as the throttle is increased(causing increased fuel and air to enter the motor), the motor would just basically fall flat on its face and die. Therefore it is advised to check the trigger/timerbase on a fairly regular basis to make sure it rotates freely in its holder as the throttle is pushed forward. If it doesn't, it needs to be cleaned and lubricated so it can operate properly. Also check to make sure linkages and connectors to the trigger/timerbase are not damaged or broken. The problem of a bogging motor can also sometimes be misdiagnosed. If you experience a "bogging" condition when you throttle the motor, and while stopped up carburators are a very common cause of this as well, first check to make sure the trigger/timerbase is not sticking and preventing the timing from advancing properly. It could save you money and a lot of wasted time when you scratch your head after finding out the carbs are actually clean as a whistle.
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