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Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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4.3 Mercruiser engine on a 2002 Chapparel 183SS. Tach not

Customer Question

4.3 Mercruiser engine on a 2002 Chapparel 183SS. Tach not registering RPMs but is counting hours (this tach has hour meter). If registering hours then the purple, black and gray wires I would think are connected and working. I have tapped the gauge to see if its stuck and also manually turned the indicator from behind to see if the needle is stuck. Even shot a small shot of WD 40- still no movement at all for RPMs
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Customer: not other than what I sent.
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Submitted: 1 year ago.
Category: Boat
Expert:  Tan replied 1 year ago.

Hello. My name is Tan.

The tach works off the signal coming from the negative side of ignition coil gray wire. The hour meter is run by the voltage from the ignition key purple wire.

The only thing you can have is a broken wire unlikely or bad tach.

The only way to test the signal coming from the coil is with a peak reading volt meter or an known good tach.

The tach is the most likely failure and is not uncommon.

Does this all make sense?

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