Bouncing tach at lower RPM

[JR IN JAX]

Yesterday I spent several hours running up/down the Suwannee. My Tachometer would begin to bounce up and down below 3000 RPM after the engine got warm. When I was above 3000 RPM [which was most of the time] the tach would work fine. I know my '98 PMAX 225 SS has a 2 stage 60 amp charging system. Could one of the two voltage regulators be going bad? The charging system has close/over 1500 hours on it.
Thanks much,
JR

[YELLOWSS]

usually it's a rectifier.. not sure with a pmax electrical system though..

[marquis4606]

not sure on a pmax either but had same problem on another boat awhile back tach was flakey for a month and could not figure it out then the stator went out put new sator on and tach worked perfect again

[JR IN JAX]

I got some good advice from friends on the Allison board to move my gray tach lead from one rectifier to the other rectifier. I'll test this weekend to see if thats the fix.
Thanks much,
JR