Tachometer help please?

[100333624]

Hello friends,

I wanna pick up a tach for my motor, its a 1978 mercury 80hp (4 cylinder) and I have the 3 pin connection at the front of the controls for the tach. Boat is a center console, but the controls are mounted on the starboard side gunwale. Its a very narrow boat so they are easily reachable when driving. Now my question is, what tach can I use that wont have wires running from the controls to the console? If I use the 3pin connection on the controls, then that means I'll have the wires from it running from the gunwale to the console and that will interfere with trying to pass through that side. What kind of tach can I get that I could just run the wires to the motor and mount the tach on the console without wires running from the sides?

 

[Texasmark]

Re: Tachometer help please?

According to my repair manual, for the Commander 2000 or 3000 remote control electrical cable, the tach connector is a 5 pin connector having:
Purple: Ignition switched 12v.
Blk: Signal ground (battery neg term)
Tan/lt blue: OT/Oil warning signal (gnd) for dash mounted visual alarm.
Gray: Tach input signal

The tach is mounted on the dash which has access under for wiring, just like the other wiring there. The control should be right there so wiring should be a straight forward process under the dash, out of sight, out of mind.

Otherwise you seem to be asking for a tach signal wireless receiver/transmitter setup and I have no earthly idea where you might find that.

Mark

 

[Georgesalmon]

Re: Tachometer help please?

The tach sender wire is either tan, or kinda brown or grey depending on the age of the motor. You can find that same wire that's on the remote control in the motor coming off of the rectifier. You can run another wire from there and you'll just need a ground wire and +12vdc and your all set. However if you can get wires from the motor to the dash why can't you run wires from the control under the deck to the dash to?

 

[100333624]

Re: Tachometer help please?

According to my repair manual, for the Commander 2000 or 3000 remote control electrical cable, the tach connector is a 5 pin connector having:
Purple: Ignition switched 12v.
Blk: Signal ground (battery neg term)
Tan/lt blue: OT/Oil warning signal (gnd) for dash mounted visual alarm.
Gray: Tach input signal

The tach is mounted on the dash which has access under for wiring, just like the other wiring there. The control should be right there so wiring should be a straight forward process under the dash, out of sight, out of mind.

Otherwise you seem to be asking for a tach signal wireless receiver/transmitter setup and I have no earthly idea where you might find that.

Mark

Commander is a quicksilver control box ya? I don't have one of those...

 

[100333624]

Re: Tachometer help please?

The tach sender wire is either tan, or kinda brown or grey depending on the age of the motor. You can find that same wire that's on the remote control in the motor coming off of the rectifier. You can run another wire from there and you'll just need a ground wire and +12vdc and your all set. However if you can get wires from the motor to the dash why can't you run wires from the control under the deck to the dash to?

Yes but does this mean that the plug on my controls has to have something plugged in? Does the tach have to be plugged into the control box? Can I not just run wires from the motor to the tach? Or do wires have to run from control box to motor to tach? I am confused this is the first time I'm doing this...

I can run wires from the controls under the deck but then I have to poke holes in the floor and I dont wanna do that... I rather run them under the deck from the transom where I have access to underneath the floor

 

[Texasmark]

Re: Tachometer help please?

Find the gray wire in your engine. For my '02 90 triple, it comes from the voltage regulator. I can't speak for other engines with other electronics or colors. Run that to your tach for the input signal along with purple for switched 12v and black for ground. Forget the connectors....just like George said.

Mark

 

[100333624]

Re: Tachometer help please?

Find the gray wire in your engine. For my '02 90 triple, it comes from the voltage regulator. I can't speak for other engines with other electronics or colors. Run that to your tach for the input signal along with purple for switched 12v and black for ground. Forget the connectors....just like George said.

Mark

So I can do this with any tach or do I have to pickup a specific type..?

 

[gbrowne9]

Re: Tachometer help please?

all tach,s run on alternator pulse.you need a positive, a negative,and a pulse signal wire coming from the rectifier which can all come from the motor.

 

[oldman570]

Re: Tachometer help please?

First you should see if you can fish a pull string from the transom area to the control tower before buying anything. You will need a tach that is adjustable for stator poles settings, as diffrent manufactures and sizes of motors are diffrent, or one made just for your motor. Then using a 3 wire 16 gauge outdoor drop cord or 3 sepreat marine grade wires long enought to reach with alittle extra to do the job. A water proof grasshopper fuse holder should be placed on the 12+ wire at the engine hookup. Once you find a way to get the wires under the deck of the boat, then you can get the needed items to do the job.
JMO
Oldman570

 

[mercurymang]

Re: Tachometer help please?

When I hooked up my tach, I was also replacing my depth guage at the same time. I used the shielded transducer wire from my old depth gauge for the signal wire on my tach. Worked like a charm. It was also at that point that I realized my rectifier was out because my new tach worked on one leg of the rectifier but not the other. I replaced it with a generic voltage regulator.

 

[Chris1956]

Re: Tachometer help please?

You can pull the correct three wires from either the control or the motor itself, as is easiest. The correct colors (original motor wiring) are black for ground, white for +12VDC accessory power and brown (or salmon) for tach pulse. If the control is newer, it may have black for ground, purple for +12VDC accessory power and grey for Tach pulse.

 

[100333624]

Re: Tachometer help please?

First you should see if you can fish a pull string from the transom area to the control tower before buying anything. You will need a tach that is adjustable for stator poles settings, as diffrent manufactures and sizes of motors are diffrent, or one made just for your motor. Then using a 3 wire 16 gauge outdoor drop cord or 3 sepreat marine grade wires long enought to reach with alittle extra to do the job. A water proof grasshopper fuse holder should be placed on the 12+ wire at the engine hookup. Once you find a way to get the wires under the deck of the boat, then you can get the needed items to do the job.
JMO
Oldman570

Running wires from the control tower to the back isnt a problem at all, I have easy access under the floor to run all sorts of things... Ok so it sounds easier than I thought. now how do I know if the tach I find is adjustable for different stator poles settings? Or which ones did they make specifically for my motor, 1978 Mercury 80hp PT/T? I was thinking of just going with a modern digital tach which is easier to read then the classic ones with the increments.. I am looking for accurate and easy readings..

 

[100333624]

Re: Tachometer help please?

all tach,s run on alternator pulse.you need a positive, a negative,and a pulse signal wire coming from the rectifier which can all come from the motor.

That pretty much sums up what I mainly needed to know.. Thank you!