QWhen trim switch on control handle is pressed tach goes to zero

[rnye14]

I have a 1996 115 hp merc, just recently, while running on plane and adjust the trim (on the control handle) the tech goes to zero. This does not happen all the time, but I am hoping someone can shed some light on what is going on and how to correct the problem. Also, how do you check to make sure the voltage regulator is charging the battery?
Thanks before hand for any responses.

 

[GA_Boater]

Welcome aboard.

On the trim/tach problem - I would clean all the battery connections and all ends of the cables. It sounds like a connection is failing.

The check the charging, put a meter across the battery and start the motor on muffs. The voltage should increase as the motor is sped up to a fast idle and the volts should raise to about 14 volts for a quick and dirty check. If that checks out, take the battery to be tested at an auto parts store.

 

[rnye14]

Thanks for the quick reply, greatly appreciated. Will try what you suggested.

 

[Chris1956]

trimming the motor takes a lot of current. If the tachometer power is supplied by the same circuit as the trim, the voltage drop when the trim button is pressed, can cause the tach to read zero. As was suggested, clean and make sure all connections are tight. If that doesn't fix it, and the battery is good, you may need to rewire tach voltage supply.