850 Tachometer Problem

[Bunky]

I have a 1974 Mercury 850 (85hp) and I have a quicksilver Tachometer...

When I turn on the key the Tach drops down to "0" but doesn't do anything then on,

I did a search and I read about changing a the Brown wire over to the Rectifier I done this and still no success....

Is there a Way to check the pulse at the Tachometer ??

or is there a Way to check the Tachometer??

 

[Chris1956]

Re: 850 Tachometer Problem

Bunky, First check continuity between the brown wire at the rectifier and the connection to the tach. If that is good, make sure the brown wire is connected to one of the yellow stator wires, and th connection is clean and tight. If still no go, put a voltmeter on the brown wire at the MerControl and ground. Set the meter for high voltage AC range, start the motoron the muffs and let it idle. Reduce the AC voltage range and see if you get some AC voltage. If so, the circuit is likely good.

 

[Moody Blue]

Re: 850 Tachometer Problem

The brown wire you referred to, was that on the non-distributor side of the engine? There is a brown wire on the distributor side (don't move that one) and on the harness connection side. This is the wire you want to move from the switchbox to one of the terminals on the rectifier.

 

[Bunky]

Re: 850 Tachometer Problem

I moved the Brown wire on the Harness side of the motor I will have to do some more checking tomm...

Someone on another forum mentioned an adapter but I don't think I need that...

 

[Chris1956]

Re: 850 Tachometer Problem

If you move the brown wire (harness side of switchbox) to one of the yellow stator wires, you may use a standard aftermarket OB tach.

 

[Bunky]

Re: 850 Tachometer Problem

Ok I found 2 problems

1) the Tack was set on #2 instead of #4

2) and I have no continuity from my harness plug to the Tach plug on the Mercontrol...

So I will have to open my Mercontrol and see whats going on....

 

[Bunky]

Re: 850 Tachometer Problem resolved

Re: 850 Tachometer Problem resolved

Ok well i popped the Mercontrol apart and the Ring terminal had came off the Brown wire put on a new one and it appears to work...

Now I just need to figure out what the idle is and adjust it...