[regency01]

I purchased a new tach from a E-bay seller. It has settings on the back for 1,2,3,4,6,8 cylinder engines. Where do I hook up the sensor wire 'S' on the Mariner 25 hp 1988 motor. See pics.
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[tashasdaddy]

i don't know the answer, but repost in the mercury outboard forum.

[Texasmark]

This is without a doubt the most confusing thing to be not confusing that I ever encountered.

I have a Quicksilver (Merc Brand) tach here on my desk. Markings on the rear say it's for "4 cycle gas or OB with Alternator".

On the selector switch are the following markings

Pos 1: 2P, 4C
Pos 2: 3P, 6C
Pos 3: 4P, 8C
Pos 4: 5P
Pos 5: 6P

This tach came off a '95 V6 engine. I'm going to guess that it has 12 alternator coils which would generate 6 Pulses per rev. Pos 5, 6P is where it operated and is where the replacement operates.
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In looking at my service manual for '94 and newer midrange engines (75 thru 125HP, 3 and 4 cylinder engines) I observed the following:

Either 3 or 4 cyl engines could use the same stator. Only difference is color (code) which indicates amperage capacity.
The stators have 8 alternator coils.
The tach hookup diagram and notes show and specifies that the selector switch should be on 4P. That makes sense; 8 coils, 4 pulses......if 12 coils uses 6P which is for 6 pulses.
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So, to get it right for your 25 hp, you need to know how many alternator coils your engine has and divide that number by 2 and that is where you set the dial.............in my opinion.

Mark

[ricksrster]

http://www.teleflexmarine.com/librar...achometer,.pdf

[Texasmark]

Thanks rick.

So, regency, since the chart says that your engine has an 8 pole alternator and the PDF file says that you divide by 2 to get the pole position, looks like the 25 hp uses the 4P position just as the midrange engines.

Will keep this in mind.

Mark