Voltage/Tach Problems

[Wild Bill from Knoxville]

2004 Mercury XR6....I have noticed that the last few times I have been out..that the voltage on the guage only reads 10-11 volts. The boat runs fine, and have not had any problems with my electronics or engine starting...until yesterday. The tach quit working. I noticed it was not working first thing...and after a few minutes..it started working...then quit again and has not worked since. I am going to assume at this time that this is related to my voltage problem (from some reseach I have done) Now for what I HAVE done. First thing I did is swap the regulators..top to bottom. The tach is only plugged into the bottom. The tach still didn't work. It only jumps when the engine is started and returns to zero. Battery voltage..after charging at home..is 13 volts. Also checked this at the red leads coming off the regulators..same same. I checked the stator...I had .3 ohms between the 2 yellow leads...and no continuity between the yellow leads and ground. This (according to my manual) tells me the stator is good. I checked the voltage at the battery with the engine running..same as before..13 volts...gave some throttle..and the voltage didn't change. What else can I do to determine if I have a bad regulator..and how do I know which one, or what else my problem may be. Corrosion isn't a problem. My engine looks brand new, I routinely spray it down with wd-40, there is no corrosion or rust anywhere on the engine.I will also post this in the Lounge for more traffic...Thanks

[EuropeanAM]

No further testing should be required.

REPLACE BOTH voltage regulators (these should be replaced IN PAIRS).

Before starting engine again:

-Load test battery to confirm it's condition.
-Clean battery terminals
-Stack ENGINE CABLE FIRST
-Remaining lugs "Largest to Smallest"
-Finish off connection with a Stainless Locknut (do not use Wing Nuts).

When finished, battery voltage (running) should remain at 12.9-14.5 VDC.

Sherm @ Sherm's Marine (or we) would be more than happy to assist you with replacement regulators.

Email or Phone are the BEST means of contacting the Parts Department(s).