# Tachometer jumping straight to 7000 RPM



## G McC (May 16, 2018)

Running a 2006 Yamaha 70 2 Stroke and as soon as I crank it up the needle on the tach gets buried in the max position. Gauge has capability to monitor oil and temp but neither appear to be hooked up. Thinking it might be a bad ground but all of the black wires coming off the tach seem to be connected fine to each other under the console but not sure where they actually go to ground, is it back on the motor somewhere? Motor seems to be running fine, idles a little rough. Bought the boat used and tach never worked right. Speedo doesn't work at all either but the tube was definitely clogged so don't know yet if that was the only issue. Considering trying a different prop but need to get the RPMs figured out to make a decision. This is my first boat but I have managed to wire some lights and do some other minor projects. Any help is appreciated.


----------



## Smackdaddy53 (Dec 31, 2012)

Probably a bad ground.


----------



## Mike C (Feb 27, 2017)

Disconnect the battery and then remove and inspect the grounds for corrosion. Treat and repeat with all of your other connections while you're in there


----------



## G McC (May 16, 2018)

Thanks guys I'll start there.


----------



## Smackdaddy53 (Dec 31, 2012)

A majority of these marine electrical issues are ground related. It’s the devil!


----------



## G McC (May 16, 2018)

Cleaned up all the ground connections I could find, took it out and still same thing. Have the tach a good knuckle radio and both the tach and the speedo starting working. Went out and came back on once in two days of running it. Also the vhf comes on randomly on occasion. Any thoughts? I have a multi meter anyway to use that to try and find the culprit?


----------



## Mike C (Feb 27, 2017)

Use that multimeter and see if the tach supply wire is grounding out


----------

