150 EFI mercury tachometer

[Scott Keling]

I have a 2001 mercury 150 EFi. When I start the motor, if the tachometer isn't working, it won't work the whole time on that run from spot to spot. But if I start the motor and the tachometer is working, it will work until I shut the motor off. It's been doing this for a couple of years. And it only works 1 out of 10 times. Any help would be appreciated.

[fishinwrench]

First remove the tach and clean the contacts and the ring terminals.

There is a dial on the back of the tach and it should be pointing to the "6P" position, move the dial around to clear the static and put it back on 6P, then reinstall the tach.

Second: Make sure battery connections are clean and tight, and inspect the gray,red, and yellow wire bullet connectors at the voltage regulator. Make sure they are clean, show no signs of excess heat, and are snapped together tightly.

Third: Take it out for a few short runs, and if the tach starts jumping around or not registering then take notice of what the voltmeter is doing when the tach is acting up ? If it is spiking above 14.4v or staying down around 12v then the outboard needs charging system troubleshooting.

If voltage is steady in the 13.5 range then replace the tach.

[Basschomper]

Thank you fishinwrench the third problem fits my 200hp 95 mariner EFI to a "T". I just thought I wasn't spending enough on a battery. Also thank you Scott for asking the question

[Scott Keling]

Thanks fishinwrench. I'll check the stuff you mentioned that I haven't checked yet. But mine doesn't bounce around at all. It either works great or doesn't work at all.

[fishinwrench]

Right on. You still have to go thru the same procedure.