I have a 2001 mercury 90 two stroke that I'm having tach problems with. About a year ago my tach stopped working and starting battery wouldn't charge, I replaced the voltage regulator and all was fine. I also checked the stator for damage and the resistance test checked out fine. After the new regulator was installed the volts gauge on my dash read 14 volts while the engine was running, regardless of rpm. About a week ago the same thing happened again, i did the resistance test on the regulator and it had gone bad again. I ordered a new regulator( the new ones come with a built in inline fuse) put it on and nothing changed, the battery was not charging and tach did not work. I traced the yellow wires from the regulator back to the stator and found both yellow wires burned in half at the quick snaps at the stator. I replaced the two yellow wires from the stator to the regulator, and the other two quick snaps that go from the stator to the spark plug coils. Now the battery is charging though the voltage is lower than from the previous regulator. Volts now range from 12.8 to 13.5 at high rpm. My tach is working some what is will read good at idle but when you increase the rpm it becomes very erratic, jumping from 3000 to 7000 back down to 4000 with just minimal throttle changes. What could the erratic tach changes mean. Did the tach burn up because of volt overload or is it telling we the stator is having problems. We checked the tach wire from the regulator to the tach all was good there too. If the tach is showing a problem with the stator or regulator how could it be charging the starting battery. Any ideas would be helpful I have run every test possible, and everything test good I just have an erratic tach.
