I have a Beta Marine 20Hp Model BD722 (350hours) installed with a 5+1 way switch panel as you can see here:
IMG00372-20110305-1016 | Flickr - Photo Sharing!
The tach worked perfect and never missed a beat until I change the services battery (not sure if problem is actually related or pure coincidence!).
All of a sudden, with the engine in motion, 5 out of 10 times it will show no reading or an incorrect reading! And if I activate a couple of the switches on the panel (eg. switch 1 - engine extractor fan) it will come to life! Switching on another switch (switch 2 - fridge) will get it to what I think is the correct rev level plus 500! And using another switch (say switch 3 - radio + vhf) will knock it a couple hunder revs down!
Any ideas what the problem could be?
Appreciate any problem areas you think might be worth investigating.