Tachometer

[Wristp1n]

I have a 1972 65hp evinrude 3cyl. that I want to hook up a tach to. I need help figuring out where to wire it to. There is one hooked up right now but the wires change color and dissapear into the harness. I have the owners manual for the motor, but it dosnt cover anything about wireing up a tach. Can someone help me?

[drasticplastic]

Before we can help ya you need to figure out what motor you have. 50hp motor is a two cyl. not a 3cyl. If the motor is a 3cyl It is atleast a 60hp motor. So find out what motor you have and post that info. Later,drastic.

[Wristp1n]

its a 65 not a 50

[drasticplastic]

Thanks for the edit in the orig. post. On an 1972 65hp 3cyl. There is a gray colored wire that is used for the tach. feed. This wire goes fromm the wire terminal strip on the power head from the position of the 3rd. screw down from the top ( not counting the mounting screw) all the way to the front of the boat into the control box. You can tap into this wire at the front or run a new wire (18 guage) from "screw #3" up to your guage. Run a new line if you question the integrity of the origional wire. Later,drastic.

[Wristp1n]

Ok i was wondering if that was the wire, but what about the other one? theres 2 leads comming out of the tach. Does the other one ground? power?
Thanks

[Gordie Miller]

have a purple, which is power through the key, gray, which is signal, bllack which is ground, and sometimes blue, which is the gauge light, if so equipped. Good luck.

[drasticplastic]

The tach. can have 4 wires 1= sensor (#3 screw), 1= 12volt dc power, 1= ground, 1= lamp/ light input(12volts dc). What kind of tach do you have? and is the light "built in" or does it have a bulb holder that snaps into a @1/2" hole in the back?.

[Wristp1n]

the tach that is in the boat (which im probably going to replace) has 2 wires... Which im going to assume are signal and power. There is no light. I think its the original tach for the boat ('76 glastron T-156) I will also be installing a water pressure gage, temp and speedo, but thats later on..... IM ON A BUDGET GAS COSTS TOO MUCH

[drasticplastic]

If the guage you have in the boat now only has 2 wires I have another question. Is the tach an omc tach?. Was the boat rigged with the motor it has now or was it rigged with an mid. 70's merc.?.

[Wristp1n]

The tach has no markings on it.. when i bought the boat it had a johnson 65 on it which blew, the motor on it right now is actually a combo between the johnson and evinrude. I used the powerhead from the evinrude i bought and put it on the lower unit of the johnson which was in much better shape. As for what was on it before the johnson. I dont know. The person i bought it from bought it used with the johnson allready on it.

[drasticplastic]

If the guage has a chrome bezel, black face and the needle mounts/pivots from the bottom of the face. It is an old mercury guage that is missing a red/orange box that delt with the guage itself only having 2 wires. With out this box the guage will not work. Does the guage look like discrip.?.

[Wristp1n]

This is turning out to be a stumper.... the guage is black plastic about 3.5 inches in diameter maybe 1.5-2 inches tall and the needle pivots in the center.. It did work a couple times but it would give off insane readings of 9,000 rpms at half throttle and stuff like that. Dont think too much on it. Like i said im probably going to replace it. Then ill send it to you so you can figure out what it is

[Wristp1n]

no chrome ring either

[drasticplastic]

Yes I agree on the get a new tach. one that you know is for an outboard motor. If this tach is for a car (4 cycle) motor and you hook it up it can cause all kinds of problems with your ignition (read expensive damage). And because I can't see the tach I would hate to say to even hook it up. The gray wire is the sensor wire at #3 screw and the wire color code the Gordon stated for modern tachs is good info. for when you get that new tach.. Yes you can send me that "old" tach. I would like to see what it is and then I can tell you. Later,drastic.

[drasticplastic]

P.S. check out your rectifyer it might have got hurt wen the "old " tach was hooked up. A bad rectifyer will not let the battery charge up and could leave you stranded.