Tiny Tach not cutting it......

[Bailey Boat]

2023 Merc 9.9 4 stroke... Installed a TT and the readings were all over the place, I changed the firings as per the instructions, no happy. Called the TECH in IL and he says wrap BOTH plug wires and run it on the 180 setting. Idle looks about right but WOT only shows 3200 rpm which I don't feel is correct.

I know there are a dozen or more induction type tach's but which one is going to work right, from your experience?? TT is off my Christmas card list....

 

[Ray Clark]

This is the one I installed on my Merc 20HP: Tachometer on Amazon

I have had it on the motor since 2021 and it works well. The induction wire is wrapped around one spark plug wire.

 

[Bailey Boat]

This is the one I installed on my Merc 20HP: Tachometer on Amazon

I have had it on the motor since 2021 and it works well. The induction wire is wrapped around one spark plug wire.

At 12.00 I'm going to give it a try, can't be any worse than what I have...... Thanks Ray.....

 

[FuzzyGrub]

Called the TECH in IL and he says wrap BOTH plug wires and run it on the 180 setting. Idle looks about right but WOT only shows 3200 rpm which I don't feel is correct.

Never heard of wrapping both plug wires!

I have used a few different TT clones without issue. Some had lo/hi filters and allot of different spark options.

I hope your new one works for you.

 

[LaqueRatt]

I just bought a TT and haven't tried it out yet. In the reviews quite a few had trouble getting it to work correctly. Hope I don't end up being one of them. Just how the heck would you know if it wasn't accurate anyhow?

 

[Bailey Boat]

At 12.00 I'm going to give it a try, can't be any worse than what I have...... Thanks Ray.....

I was wrong, it IS worse than the TT. I can get either correct idle RPM's or correct WOT RPM's but not both at the same time. And speaking of time, I ran the engine about 2 hours yesterday and it recorded 16 hours!! At this rate it will be worn out before it's broken in..... I'm at a loss to understand why SOMEONE can't make one that works...

 

[Ray Clark]

I was wrong, it IS worse than the TT. I can get either correct idle RPM's or correct WOT RPM's but not both at the same time. And speaking of time, I ran the engine about 2 hours yesterday and it recorded 16 hours!! At this rate it will be worn out before it's broken in..... I'm at a loss to understand why SOMEONE can't make one that works...

"can get either correct idle RPM's or correct WOT RPM's but not both at the same time"

I'm not understanding the comment. The unit only displays the RPMs it senses at the instant. How can the motor be operating at idle RPMs and WOT RPMs at the same time?

Regarding the time the unit recorded, I think I'd zero out the unit and try again and see what happens. If it happens again, return it.

 

[LaqueRatt]

Tried mine out and it seems just fine. I was just interested in idle speed, but my "by ear" tune was within 50 revs, so I'm calling it good. Did you notice there are 4 different modes for different motors? Maybe you have yours set wrong. Could that maybe acct for the running hours being inaccurate as well?

 

[wmk0002]

Its probably getting interference. I've had that issue before on tachs that I know work but were erratic on another motor. I was never really able to figure what was causing it though. Try moving it up and down the plug wire. Also try routing the wire through something like some scrap fuel line or a piece of wire loom. FWIW it always takes some fiddling for me on Yamahas but seems to work better on OMCs. May be coincidence though lol.

 

[FuzzyGrub]

Try less loops around the spark plug wire. Try the other spark plug wire. Try the hi/lo setting if it has that function.

I did some quick searches on "Tohatsu Tiny Tach". While not sure if it applies to your 2023 9.9, the 9.8 used a simeise coil and fired on each revolution.

 

[SAABologist]

Thinking of trying one of these. Will it still work if you splice in additional wire so I can run it up to the console? Thanks.

 

[FuzzyGrub]

Thinking of trying one of these. Will it still work if you splice in additional wire so I can run it up to the console? Thanks.

I would not recommend that. It will likely pick-up too much noise. On the other hand, once you verify it works "as is", won't take much effort to try it and you can revert it back.

 

[thill]

You can wrap both plug wires, and set it for 4 stroke, but a single wire wrap and 2 stroke setting should work well, regardless of RPM.

I got tired of tiny tachs and got one of these for my bigger boat with a dash:
https://www.amazon.com/gp/product/B07JW2ZRZ8
And one of these for my jon. This is not the exact one, but similar. Much happier with it than the tiny tach:
https://www.amazon.com/DriSentri-Tachometer-Gauge-52mm-Blue/dp/B0BC183ZGC

 

[SAABologist]

I bought a cheapo regular tach and will hook it up to the Mariner 40 and hope it lasts.

 

[Bailey Boat]

You can wrap both plug wires, and set it for 4 stroke, but a single wire wrap and 2 stroke setting should work well, regardless of RPM.

I got tired of tiny tachs and got one of these for my bigger boat with a dash:
https://www.amazon.com/gp/product/B07JW2ZRZ8
And one of these for my jon. This is not the exact one, but similar. Much happier with it than the tiny tach:
https://www.amazon.com/DriSentri-Tachometer-Gauge-52mm-Blue/dp/B0BC183ZGC

And on the jon boat what did you tap into to get a signal?? I can't find anything in the wiring diagrams that would work for a tach....

The tach has 3 settings and I tried them all with no acceptable results. I get EITHER idle correct, OR WOT correct based on the setting , NOT both at the same time....

 

[GilK]

And on the jon boat what did you tap into to get a signal?? I can't find anything in the wiring diagrams that would work for a tach....

The tach has 3 settings and I tried them all with no acceptable results. I get EITHER idle correct, OR WOT correct based on the setting , NOT both at the same time

Did you get it figured out yet?
I've got a '99 Yamaha 15 4 stroke and need to get a tach to get the right prop.

 

[Still Afloat]

I recently installed a Tiny Tach on a Suzuki DF20A. Seems to work fine. I just did one snug wrap, added a couple of twists to hold it in place and cut off most of the excess wire. Also grounded it fairly close to the pick-up loop.

 

[GilK]

Tachometer for Small Engine,Inductive Hour Meter for 2 Stroke & 4 Stroke Small Engine, Timorn Replaceable Battery Waterproof Tachometer for Chainsaw Marine ATV Motorcycle UTV Engine (Black) https://a.co/d/d1QrZ1z

I just ordered this. I'll let you know how it does.

 

[AZGDOGG]

Tachometer for Small Engine,Inductive Hour Meter for 2 Stroke & 4 Stroke Small Engine, Timorn Replaceable Battery Waterproof Tachometer for Chainsaw Marine ATV Motorcycle UTV Engine (Black) Amazon.com

I just ordered this. I'll let you know how it does.

I have one of those on a 10 hp Mercury Sea Pro, do not wrap sensing wire too many times around plug wire. When I first installed it I wrapped the sending wire about six times around the plug wire and used a ty-rap to secure thinking more was better. Wrong. It will give you erroneous readings. Probably only need a wrap or two, then secure using small ty-rap, experiment with it before final assembly. Mounted unit it to the engine using existing unused screw holes in block and correct machine screws and washers. Good luck!

 

[Still Afloat]

It‘s probably best to read and follow the instructions. The Tiny Tach instructions said one wrap. That’s what I did and no problemo.