Need some help for Yamaha ob

[Joe Walsh]

I have an 05, 250hp, Yamaha. It has an intermittent tach. Display reads "0", when not registering rpm's, so I know it still has power. It seems to come and go, when I trim motor. Any suggestions where to start trouble shooting? Motor run perfectly. Any help will be greatly appreciated.

Joe
"Celtic Charm"

[Skip]

FWIW: Over the years - I've found the ground often to be the culprit on 12 volt systems. The ground wire is often black on 12 volt.

I'd follow the ground on your tach to see if the connection is tight and clean.

You'll never do any harm undoing it and cleaning it. I use a small file to shine the connections - then follow with electronic spray cleaner.

While under the dash - might be wise to remove and clean any connection related to tach ( one at a time ).

If really handy - figure wires out at engine as well to verify they are clean.

The main ground on battery also should be looked at.

[Joe Walsh]

Thanks Skip, I was thinking along those lines.

[Skip]

Reread your post - might want to check the positive ( red ) on battery as well.

Sounds like engine trim is drawing too much.

Other thing to check is battery itself - especially if 3 to 4 years old.

[Joe Walsh]

Skip, when I say it comes and goes, sometimes when trimming motor, it's not just when t/t motor is operating. It's intermittent, but it will stop registering anytime, and sometimes can get it to register by hitting t/t..I also can lose it, when I hit t/t.. Battery terminals are clean, and both batteries are good.