Tach question

[fishinchef]

I have a Mariner 150 outboard and the tach just quit working. The motor is running fine. At Idle, the needle is on zero but when you raise or lower trim it will jump a little. Could this be a tach problem or something electrical??

[offdtop]

How much is a little? You may need to check the line going to the tach

[EtecRanger205]

Check to see if the motor is charging the battery when it is running at idle, then does the voltage increase when you increase the RPMs. If it does not than you need to replace the
voltage regulator (VR). The VR also drives the tach to work. Good luck.

[fishinchef]

Thanks for the tips.
I noticed this summer when running at night the stern light would go "Dim" when using the trim button. Figured it might be the battery since it was a few years old. Will check the VR and see if that helps. Thanks again for the info guys

[buzzking]

You should definately check this ASAP, a disfunctional tach can fry the ECM pretty handily. And thats no cheapo fix.