Cannot get Tach to work on 1983 Merc. 70hp

[BassAssassin]

Howdy, i cannot get my tach to work for the life of me on my old merc. i have tried runnig a line from the rectifier but i didnt know which of the four bolts on top to hook it up to. i tried 2 of them but does anyone know for sure? i have hooked it up through the merc control using the brown wire which i believe is the signal wire. also the tach could be bad so is there a way to test it out before i buy a new one? any othe ideas would help also. thanks

 

[Laddies]

Re: Cannot get Tach to work on 1983 Merc. 70hp

Try jumper wires at the rect, Yellow to signal and grd to - if it don't work then you have a bad tach

 

[BassAssassin]

Re: Cannot get Tach to work on 1983 Merc. 70hp

i have tried to wire it from the rect but i dont know which wires to go from. the only yellow wire from the rect goes to the bottom of the starter motor. there are 2 big bolts/studs and 2 small bolts/studs. am i using the small bolts or big ones? its hard to tell the color of the wires. any additional help would be appreciated. thanks

 

[Laddies]

Re: Cannot get Tach to work on 1983 Merc. 70hp

thats not the rectifier thats the starter solinoid the rect is small 1 1/2 by 1 1/2" box with 2 yellow wires from under the flywheel and a red wire that goes to the solinoid either yellow will work

 

[BassAssassin]

Re: Cannot get Tach to work on 1983 Merc. 70hp

ahhh lol well that would explain that. its under the flywheel? do i have to take the fly off or is it accessible? thanks a bunch.

 

[rolmops]

Re: Cannot get Tach to work on 1983 Merc. 70hp

Bassassasin,the yellow wires come from under the flywheel and go to the rectifier which sits on the front side of your engine,it is that little box that you should easily see.It has 2 yellow wires going to it from under the flywheel and a red one that goes to the power supply.

 

[Laddies]

Re: Cannot get Tach to work on 1983 Merc. 70hp

Thanks rolmops he needs the help and I was away on honeydos---Bob

 

[BassAssassin]

Re: Cannot get Tach to work on 1983 Merc. 70hp

yes indeed i doo need help. this is my first boat and it has needed a ton of work so far, but i couldnt do it without the help of this page.<br /><br />that being said i hooked up a direct line from the rect. to the send part of my tach. the rect had 2 yellow wires the red and a brown(that i assume goes to the mercontrol). still i got nothing. what else should/can i try? any oter ideas? is the rectifier bad? i know that the battery charges so if the alternator goes through the rect. it wouldnt charge right? thanks and sorry for being a pain.

 

[Laddies]

Re: Cannot get Tach to work on 1983 Merc. 70hp

Your tach must be shot and yes the brn wire hooked to the yellow termenal is the sender wire to the control----Bob---and your not a pain