1996 Mercury 135L - speed surge, tach and speedo issues

[xsivhp]

I picked up a Lund boat with a 1996 Merc 135L on it - the motor seems to run great with a couple issues.

- The tach doesn't work (found this post https://forums.iboats.com/forum/eng...0-1996-mercury-135hp-voltage-regulator-repair )

- the speedo doesn't work

- when cruising about 20 and easing the throttle up a little it seems to accelerate on its own and then the speed is a little faster than I wanted it to be.

I've searched the web high and low on this motor and there is not a lot of info on it from what I can see so I am thinking either there weren't a lot of them built or they have very few issues .... or I'm just not looking in the right spot!

Thanks in advance for any insight you can provide.

 

[Chris1956]

There were a lot of those motors built, as they were manufactured for many years, with minimal changes.

The tach runs off the grey wire. I would suggest you check it for shorting to ground. Also, if the VR is bad, the tach may not get a good signal. You can swap it over to the other VR.

Check the VR units for burn marks on the circuit board. It is probably best to replace in pairs, if they have burn marks. You can also check the voltage at the VR, with the motor running on the flusher. If it is above 12VDC, the VR is working..

As for the cruising issue. You might check the link and synch. Perhaps the carbs are out of synch with the spark timing? It's a guess.

 

[xsivhp]

Well I swapped the wire and the tach still doesn't work. I'll check the VRs and see what the voltage is. Thx for the reply!