2003 J90plstc tach issue

BenP

Cadet
Joined
Jul 5, 2015
Messages
6
[FONT=Helvetica, Arial, sans-serif]So I just replaced my tachometer gauge with a new tach and I am still having issues. the tach stays at 0 rpm when motor is on and in idle then when i start going it goes up to 2k to 4k rpms but bounces all around that range. do i need to replace the Rectifier/Regulator. My battery has never gone dead on me although I dont know what it is pushing out. would anything else be causing this? I can not imagine it would be anything besides the rectifier regulator if the needs is bouncing between 0 and 4k rpms when I am going and then at 0 rpms when idle. The battery has never been dead and I have actually never had to charge the main battery either. The part number I need is [/FONT] [h=3]Part# 0586075 . and is only 210.00. Seems like I should just replace it instead of spending money testing i have already replaced the old tach and still have the same issue. Would I need anything else besides the part to replace the old rec/regulaotr? thx for the help[/h] [h=3][/h]
 

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Put a voltmeter across the battery once when running it and see what kind of readings you get.
 

rothfm

Ensign
Joined
Sep 26, 2006
Messages
915
2nd Vote for the CDI troubleshooting procedure. But sounds like the Rec/regulator....However I once had a wierd tach bouncing issue, and at the times it would bounce, my warning Horn would make a medium volume "scratching" sound, a really odd non-rythmatic "static" like sound.. My issue turned out to be corroded grounds through the motor. Now Im a stickler on periodically removing all connections and ensuring all are clean.
 

David Young

Chief Petty Officer
Joined
Jul 12, 2015
Messages
485
Another vote for a bad Rectifier. When mine went bad the tach was going crazy. With the motor off the battery would show 12.5 volts and running it would show 12.7 volts. Changed the rectifier and the battery would show 12.5 volts with the motor off and over 14 volts with the motor running. It fixed the tach :)
 
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