Tach signal

M

my1stboat1

Petty Officer 1st Class
Joined
May 31, 2010
Messages
307
Tring to install a tachometer on my boat.. ( did not have one before ) 1988 bayliner with 85 force outboard... Where can i Pick up the tach signal at the engine from....

thanks
 
C

cambosoup99

Seaman
Joined
Feb 22, 2010
Messages
69
Re: Tach signal

If you look on the starter side of the engine you should see a rectifier with 4 wires come connected to it. 2 are ac power; 2 are for dc. You need to connect the tach to one of the ac wires. colors are green with yellow strip. When you hook it up if your tach acts funny then try the other ac wire.
 
roscoe

roscoe

Supreme Mariner
Joined
Oct 30, 2002
Messages
21,667
Re: Tach signal

There is usually already a wire connected up, running to the terminal strip, into the main wiring harness, and up to the controls and ignition switch.

Depending on the year, it could be grey, white, or purple.
 
J

john from md

Commander
Joined
Apr 13, 2008
Messages
2,184
Re: Tach signal

In case no one has told you, you must use a 20 pole tach for the older Force engines. They are hard to come by but sometimes they can be found on ebay.

The tachs you buy from Westmarine won't work.

John
 
M

my1stboat1

Petty Officer 1st Class
Joined
May 31, 2010
Messages
307
Re: Tach signal

20 pole ? so im assuming that the tach that i just bought for 80 bucks and destroyed the plastic covering to get it out of cause they wrap these things in an impossible manner isnt going to work LOL....


that stinks...

what does 20 pole mean.. ???
 
J

john from md

Commander
Joined
Apr 13, 2008
Messages
2,184
Re: Tach signal

The alternator on the early Force engines had twenty poles. Thus, the tachometer had to have the same amount of poles in order to read correctly. Some of the new tachs have a selector switch that goes from six to twelve but never twenty. Twenty pole alternators are old technology.

You can find them on ebay sometimes and can canvas boat dealers as most of them have things like that laying around.

John
 
M

my1stboat1

Petty Officer 1st Class
Joined
May 31, 2010
Messages
307
Re: Tach signal

hey john your pretty resourceful... my question is that i just bought a really nice set of gauges.. since i just read the gauge that it is 12 pole... is there a way to make the engine work to except a 12 pole tach... what would needed to be changed...


thanks man
 
J

john from md

Commander
Joined
Apr 13, 2008
Messages
2,184
Re: Tach signal

You might try asking that on the Electronics forum. There was a guy playing around with an idea on how to make less than 20 pole tachs work with 20 pole alternators but I don't know how far he got.

John
 
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