1997 - 200 Merc : Replaced Rectifier/Volt Reg but Tach still runs high?

[frillici]

I had an over voltage confition running 16V+ on the Volt Meter. Replaced both Rectifiers/Voltage Regulators but still get a highy running tach - she seems to be about 2000 RPM too high. Also, my trim indicator is stuck in the full-up position, but I think that may be unrelated and need a new sensor at the tilt bracket.

Also, just installed a temperature gauge (Mercury OEM) and it does not move off the initial 60 degree line.

Could I have fired something - where do I start.

Guidance much apprecaited.

 

[hkeiner]

Re: 1997 - 200 Merc : Replaced Rectifier/Volt Reg but Tach still runs high?

The below linked Teleflex website has some guidance on troubleshooting gauges and such. This will tell you what to check and how to check it. Report back on what you did check and your results to get more specific advice, if needed.

http://teleflexmorse-eu.com/newgauges/guides.html

 

[frillici]

Re: 1997 - 200 Merc : Replaced Rectifier/Volt Reg but Tach still runs high?

Ensign - thank you. that is a great link and provides a lot of information on instrumentation. While a wrestle with my tach problem.

On my Mercury, there are two temp sensors. Port is the high temp alarm and starboard is the variable temperature indicator 60-220F. I just insatalled a new gage - never had one on this motor. The schematic shows a direct brown/blue wire running to the "S" on the gauge. My engine has the temp variable sensor brown/blue wire going to a block and then connects to the brown/blue wire that goes to "S". On the block, located on the starboard side aft of the starter, there are other wires connected and they lead to a "black" retangular box that sits on the top/port side of the engine. Any idea what this "back" box is - looks like a controler/regulator and should I wire the sensor direct?

Being a backyard mechanic is so much fun - any insight appreciated.

 

[frillici]

Re: 1997 - 200 Merc : Replaced Rectifier/Volt Reg but Tach still runs high?

I just found a section in my new mercury manual that explains. The other wire goes to the electronic control module (ECM) to reduce speed to less than 3,000 RPM in an overheat situation. I am now good - so thank you.