Faria tach acting funky

[bonz_d]

With the help of some good folks here I was able to attach my tach to my 1978 Evinrude 35hp. When I 1st ran it in the tank everything seemed to be fine. Yesterday was actually the 1st time I've been able to test it on the water and this thing is all over the place.

At idle it's now showing 2000 rpm. Throttle it up and it goes up smoothly to 3000 rpm then drops off a bit, sometimes as low as 1500, then comes back up and will go as far as 4000 rpm at wot. I know this thing is turning more than that at WOT.

Any ideas as to what could be wrong other than the tach is hosed. Wish I had another engine to test it on but I don't.

I checked Farias web site and the tach is set correctly for 10 poles to the #4 setting. Have also checked the charge output with a good digital volt meter and it looks like it is charging fine.

When I wired this I had to run a seperate wire to the motor because the wire cable to the control has a black plug with only 5 wires with no wires for a tach. So could I be getting electical noise through this wire to the stator?

 

[Togman]

Re: Faria tach acting funky

I am having the same problem on a 1999 Johnson 30hp with a Faria Tach. I replaced the rectifier & the same thing happens. Any idea?

 

[bonz_d]

Re: Faria tach acting funky

Togman, I haven't come up with a solution for this yet either.

Is your tach connected to the plug coming from the control?

 

[jimg984]

Re: Faria tach acting funky

make sure the tach wire on the rectifier is connnected to one of the stator wires FEEDING out from under the fly wheel. how many wires are coming out from under the flywheel? if 4 two of the wires will be a feed a coil which becomes a magnet for the stator.. again needs be on one of the two FEEDING out GL

 

[Phantom_II]

Re: Faria tach acting funky

It could easily be a bad tach.

My Faria started acting up last month. Idles at 2000 RPM, 7500 RPM at WOT, but if I tap lightly on the face of the tach, it drops back to normal.

I need to get a new one but it's not very high on my list at the moment.

 

[bonz_d]

Re: Faria tach acting funky

My 35 has a 4 wire stator and I have the tach connected to one of the yellow wires on the terminal block.

This tach is from ebay and was supposed to be a "new" unused product. So this tach could be suspect.

The only reason I was going to use it was so I could get a WOT RPM so I could properly size a new prop.

May go to a Tiny Tach instead of the headache.

 

[Togman]

Re: Faria tach acting funky

Quote: "Togman, I haven't come up with a solution for this yet either.

Is your tach connected to the plug coming from the control?"
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My Faria Tach plugs directly into a big square plug from the wiring harness from the motor. It has the "System Check" lights built into it. All wires are tight, so I am at a loss as to why it is inaccurate.