rev counter stuck(tacho)

[piperdog]

hello,it was working great ,then looked again ,it had stuck on 4000rpm ,disconnected power ,still stuck tried tapping ,but no joy ,its on a merc 65hp,1965,any ideas (apart from the broken idea ) thanks piperdog

 

[Barnacle_Bill]

Re: rev counter stuck(tacho)

Are you sure you are getting 12V to it? If you happened to lose power to it while the motor was running at 4K, then it will stay there until power is restored. They normally go to 0 with the key on and motor not running.

 

[Yepblaze]

Re: rev counter stuck(tacho)

Is it still "stuck" when running?

The question I ask, because it's not uncommon for some tachs to react to static charge, but be otherwise fully operational.

As I shined the dash on the old boat last week I think I hit almost 5000rpm once just wiping over the tach with the static charged rag.

 

[piperdog]

Re: rev counter stuck(tacho)

stuck when running,stuck with battery connected and disconnected,looking at a wiring diagram ,the wires connect to the go/stop lever control box ,one goes to the engine ,others are coonected to switches in this box,can you tell me where it goes on the engine and if i disconect the wires from the a/m box can i test by putting power to the wires .thanks piperdog

 

[Barnacle_Bill]

Re: rev counter stuck(tacho)

Find the power input on the back of the tach. Use a meter or test lamp and verify you have 12V there with the key on. If 12V is present, replace the tach.

 

[piperdog]

Re: rev counter stuck(tacho)

thanks for the reply,but if dont have feed ,where does it come from on the engine..

 

[Barnacle_Bill]

Re: rev counter stuck(tacho)

thanks for the reply,but if dont have feed ,where does it come from on the engine..

Power for tachs is normally tied into the ignition switch.

 

[piperdog]

Re: rev counter stuck(tacho)

three wires going to the tach,one will be earth ,one will be switched positive ,as you said,and one goes to the engine ,ideas where this is connected to,thanks again ,piperdog