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Another Tach Wiring Question

U

Utilo

New member
I just bought a new Faria tach for my 30' SeaRay. The wiring initially seemed pretty straight forward, black, purple, grey, and blues wires.

Until....I started removing the old tach and found 3 purple connected, 3 blacks connected, 1 grey, and 2 blues.

I haven't yet traced where all those wires originate but....is it safe to assume someone got a little over exhuberant when wiring the old tach?

I can't imagine why someone would connect 3 black ground wires......3 purple power/ignition wires.....2 blue wires going to the light terminal.

I'm inclined to remove/abandon a bunch of those wires and get back simply to the 4 wires only that I believe I should need.

By the way....I wonder if all this...what I believe to be excessive wiring.....could possibly have been the cause of my erratic tach operation to begin with and maybe I didn't even need a new one.

Thoughts please?

Thanks.
 
Last edited:
The boat wirer probably used the Tach. wire studs for junction points rather than tying the colors together and attaching a single pitail wire to the tach.
 
The below diagram is a general way of hooking up instruments.
What is important is that the signal wire is 'single', which yours seems to be.
(1 grey).
Erratic tach in your case might be caused by bad connection(s) in the Grey wire from tach to engine, defective tach or simply missing ign pulses.
 

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They wire the ground in series which means that if you pull all but one black ground you will lose ground to something else down the line. I doubt if that caused your tach problems. Either your tach is corroded inside or you have a corroded or loose wire some where else. Have you hooked up the new tach yet?
 
"Have you hooked up the new tach yet?"

I've got all the wires connected....but haven't run it yet. Turned on the key once and the tach went to "zero" but that's as far as I've got. I'm sure it'll be fine.

Next time down at the boat...likely this weekend, I'll fire it up to see what it does.

Just waiting to get another pair of hands to help hold the tach in position from the front while I'm behind the dash tightening the hold down bracket.

"Either your tach is corroded inside or you have a corroded or loose wire some where else."

All the wiring behind looks fine. No corrosion evident anywhere and tight connections.

I'm sure the old tach was simply faulty.....sitting at Idle....it would sometimes start to slowly climb on it's own as high as 4K to 5K RPM. A little touch on the throttle and it would go back down. Other times the needle would bounce around etc etc.
 
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