Tac Issue

[Nickledimed]

I just bought a tac and wire harnes for the tach.
I set the tac at 6c 6p.
Now, the tac will only register when I get her up to about 3000 rpm.
Any lower and it starts to work intermitently.
She doesnt read at idle.
I have a 1983 inline 6 115 merc.
The tac I got off of Iboats 3461316
There is no setting for 12p on the tac which from what I understand is what the tack should be reading.
Any help is welcomed
Thanks

 

[Barnacle_Bill]

Re: Tac Issue

6P is the correct setting. Test your rectifier. I believe this is the one you have.

Testing Merc?s square rectifier

If you use an analog meter set it on the RX1000 scale.
If using a digital meter, set it on the diode symbol.

1. Disconnect the battery leads.
2. Disconnect all wires on the rectifier.
3. Connect the red test lead to ground and the black lead alternately to terminals A and C.
The meter should show continuity.
4. Connect the black lead to gound and the red lead alternately to terminals A and C.
The meter should not show continuity.
5. Connect the black lead to terminal B and the red lead alternately to terminals A and C.
The meter should show continuity.
6. Connect the red lead to terminal B and the black lead alternately to terminals A and C.
The meter should not show continuity.
7. Replace the rectifier if you do not get correct readings.

 

[Nickledimed]

Re: Tac Issue

Thank you.
I will perform this test tomarrow.

 

[Nickledimed]

Re: Tac Issue

I did the test and it shows that b has no contenuity.
I found a new one for about 35 dollars, I will pick it up tomarrow.
Thanks,
This probably explains why the motor hasnt been running properly.
Im not sure how long this has been this way.

 

[Nickledimed]

Re: Tac Issue

Now, anouther issue with the tac.
I took the boat out this weekend and the tac was doing some weard stuff.
It would jump from 5000rpm to 6500rpm.
Then it would drop to 0, bounce back up to 5000rpm.
At some times it would read correctly but continue to bounce around.
Any Ideas?
Engine runs like new.

 

[Nickledimed]

Re: Tac Issue

bump.
Can anyone help?

 

[westexasrepublic]

Re: Tac Issue

replacing the rectifier solved my problem, so I dont know for sure, but sound like a loose wire on the back of tac, does it normally jump around just ideling or when in motion? loose wire vibrating around under way is my guess.

 

[daveswaves]

Re: Tac Issue

replacing the rectifier solved my problem, so I dont know for sure, but sound like a loose wire on the back of tac, does it normally jump around just ideling or when in motion? loose wire vibrating around under way is my guess.

Don,t mess with Texas, I think he is right, sounds like a bad connection.

 

[Nickledimed]

Re: Tac Issue

You know..ill bet thats what it is.. loose wire.
Ill check it out when I get home.
thanks..