189TRX Tach Adjustment

[ford4wd08]

Just for anyone else who has a Faria Tach on their 189TRX with a 4 stroke, I reached out to the company today on how mine was reading way off at WOT.

They sent me some information on how to fine adjust the tach.

For my application, I would assume all Mercury 4 strokes, they told me to set it on position "5" and then use the fine adjustment pot to dial it in and match my vessel view mobile.

This was the first I had heard of that and thought I would pass that on. I don't always use my vessel view mobile, but would like the analog tach to be as close as possible.

[ecoast]

"5" is not ALL merc 4 stroke; there is a legend to each setting...tach will work w/ 3,4, 6 cyl motors depending on setting

[DaveTTN]

Mine reads 500 rpm too high.

[RangerNate]

I have a thread about this in the Mercury 4 stroke forum. Don told me another setting to try. I haven't been able to get accurate idle or wot readings set at 5, even with the fine adjustment. My next trip out I am going to try every setting, and bring another tach.

[thommo59]

My first Faria tach was faulty and reading around 1500rpm too high and the small adjustment would not tune. They replaced the gauge and I tuned it against my vessel view mobile and it’s now within 100-200 when in the 3,000 to 5650 range. I’m not concerned at low rpm’s and took a few runs to dial it in. Reality is they just aren’t accurate.

[RangerNate]

"Reality is they just aren’t accurate"

Although I am still messing with mine, I think this is the reality. I am trying to figure out if it is a junk gauge or an incompatibility between the engine and tach.

[RangerNate]

I wanted to make an update:

I tried every setting on my tach and using the fine adjustment pot. Nothing I did was even close. Today while on the lake I decided to mess with it some more, being that the fishing was slow. So here is where things get a bit mad scientist, or dumb redneck. I turned the dial to the "click" before position 1, and somehow it works. I did not even touch the fine tune trim pot. It is now accurate through full rpm range verified by vessel view. I have to assume my tach is defective, but it worked the rest of the day. I will update if it quits working or breaks the space time continuum.