Using an automotive Tach on a Tohatsu 9.8A3

[JulianDave]

I'd like to check my RPMs at idle on my 2012 Tohatsu 9.8A3 and have a Sunpro CP7603 Dwell/Tachometer. It has 2 wires: One to ground and one to the negative side of the coil.

There is a white and yellow wire on the outboard for the factory tach. The yellow is ground, but the white goes straight to the CD Unit. Can I connect my tach to that? The outboard coil has an orange and a black wire coming from it. Should I connect to one of those instead?

I thought I'd try to use this tach since I have it, but I don't want to screw anything up by connecting it to the wrong thing.

[Sea Rider]

That's a 4-6-8 cilinder tach, probably wont work well on a 2 cylinder engine ? Better buy a induction Tiny Tach or Hardline hout/tach.

Happy Boating

[JulianDave]

Both of those tachs look nice. I have the tiller outboard on an open, jon style boat. Are tachs ever mounted directly on the outboard? As the motor is on and off the boat all the time, I don't know where else it could be mounted. Having an hour meter would be really nice.

[pvanv]

You can mount some tachs on the motor, but any mechanical-movement tachs will probably suffer from vibration. If you use a Factory tach, you can add a 2-wire waterproof disconnect near the motor to take the motor on and off.

[Sea Rider]

Have mounted Hardline hour/tachs which are slight less bulky that TT at engine front, some mounts them at tiller arm, you can use the sefl adhesive or screws that are provided for both brands. Have not had any issues with vibration whatsoever as both are electronic buit. Assume if using original Tohatsu tachs will need a console or a proper mount to install ? An hour/tach is the way to go, excellent for adjusting rpm at idle, knowing max rpm at wot, playing with props and hour meter for preventive maintenances, plug clean/change, oil tail change, etc and total horse run hours.

Happy Boating

[JulianDave]

Thank you for those photos. I was thinking that it has to be mounted on the outside somehow, but when you adjust idle you have to have the top off anyway. With an hour meter built in, these really are a mandatory accessory.

[Sea Rider]

If your engine has available front space as in pic 1 install it there if you would like to look at the tach rpm readings when boating, if not could install inside engine, just find a proper place to secure. Anyway only need to adjust idle speed once. Both meters counts rpm/hours, displays rpm while engine is on, displays total worked hours when engine is off, as stated before ideal for many nice aplications including break in periods. Go for a tach/hour meter of reputable brand and warranty, are cheap, works perfect and are installation friendly.

Happy Boating