Tachometer on 1999 70 HP Johnson

[David C]

Hello,
I am new on this site and need help.
I bought a used 1999 70 HP Johnson outboard for my boat and had it installed by the mechanic that I bought it from. After the install of the motor my tach would not work. He told me that the tach was bad and needed to be replaced. I replaced it and still had the same problem. I have since replaced the voltage regulator and still no fix. (Long story)
I tested the voltage on the gray wire at the back of the tach and I get negative voltage with the motor running. All other test on the tach show the correct
(positive) power and ground readings. This is the same with the gray wire connected to the tach and with it not attached.
Can anyone offer any help with this one?
Thanks in advance,
David

 

[rickdb1boat]

Re: Tachometer on 1999 70 HP Johnson

Hi David

Check voltage at the battery with the engine off. Then check it again with the engine running at fast idle. You should see an increase. If not, you still have regulator/rectifier charging problems which affect the tach....

 

[David C]

Re: Tachometer on 1999 70 HP Johnson

Hi David

Check voltage at the battery with the engine off. Then check it again with the engine running at fast idle. You should see an increase. If not, you still have regulator/rectifier charging problems which affect the tach....

Thanks for the reply.
I will check that with the changed out regulator tomorrow. With the original regulator the voltage on the battery would increase with the engine RPM. At least according to the battery status guage and the volt guage on the dash. The mechanic told me that could happen and it still be a problem with the regulator. I am limited in this area for trust worthy places to get to work on this. Thanks for any and all help.
David

 

[David C]

Re: Tachometer on 1999 70 HP Johnson

With the original regulator I have charging. I do not with the replacement regulator. The tach will work if I put the gray wire to the tach on the yellow and gray wire from the regulator but I have no charging with it wired this way.
I had a mechanic try a third regulator that was know to work. The result was the same, no tach with everything connected ccorrectly.

Thanks
David

 

[ob]

Re: Tachometer on 1999 70 HP Johnson

The yellow/gray and the yellow wires are unregulated voltage 18-20 a/c from the stator to the regulator.The secondary from the regulator is gray/tach and red/dc voltage.What you now need to do is install a known working regulator and a known working tach.

 

[David C]

Re: Tachometer on 1999 70 HP Johnson

The regulator is working fine now. Someone had cut and taped the purple wire back in the wiring harness. The regulators was not getting ignition power. Thanks for the help with trying to get this fixed.

David