115 mercury tach not working

[Grumpy]

OG141941 1995 mercury 115. Tach has not worked since I bought the boat used. A friend let me borrow a tach to try and nothing. Motor is charging shows 13.8 volts on gauge. Could previous owner have used after market regulator be the problem. Any help would be appreciated

[silvertalon]

Check the grey wire from the regulator to the harness. Doesn't matter if it has an aftermarket reg on it. It either works or doesn't.

[Grumpy]

Thank you

[Grumpy]

Checked gray wire it’s fine. Ordered a new tach to try

[silvertalon]

If you can get a dc voltage reading from the grey wire (will vary with rpm's), then the reg is probly ok. If no voltage output then it is defective. Most tach's are fairly reliable. They should zero out when you turn the key on. If not, check your 'key on' ignition volts and ground at the back of gauge. . You can find aftermarket reg on the big 'E' for cheap. Will work just fine. OEM is always recommended however.

[Grumpy]

Thank you

[Grumpy]

Ok installed a new tack and checked gray wire from motor to tack. Tested ok. Started motor 90% of the time tach does nothing other 10% it randomly starts moving but is inconsistent in its readings. Any ideas.

[JOE54]

would prob junk regulator

[Grumpy]

Thank you