1989 johnson 88spl rectifier getting hot!

derail69

Recruit
Joined
Jan 25, 2015
Messages
1
I just bought a 1989 88spl mounted it on my kenner started it up on the muffs to make some adjustments and smelled wires burning! Felt around the area of the smell and the rectifier was SMOKING HOT! I only ran the motor for about 2 to 3 minutes and its hot. whats causing this?
 

Vic.S

Rear Admiral
Joined
May 4, 2004
Messages
4,690
Battery connected with polarity reversed? If so rectifier now toast!
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Are the main cables to the battery secured tightly? Both on the battery and engine ends. Any corrosion on the connection ends? Are the cables frayed, any wire threads broken-reducing the effective size of the cable?
 

gm280

Supreme Mariner
Joined
Jun 26, 2011
Messages
14,585
Very odd situation. Personally I don't see reversed battery wires because for two issues. First the starter would have never turned over the engine, and secondly the rectifier would have been toast long before this. It sounds like the output from the rectifier unit is shorted to ground and when the stator is producing output voltage the rectifiers are dumping the current straight to ground. And that WILL heat them up and eventually, if not already, burnt them open... But not being there and seeing everything myself, this is only my guess...
 

Crosbyman

Rear Admiral
Joined
Nov 5, 2006
Messages
4,907
why not disconnect the battery and accessories and test the +12 v for any grounds. with the battery off and accessories switched out you should see nothing to ground on the +12 distribution. reconnect the battery with accessories off and ignition off.... the +12v post should show no sparks at all if it does find out why.


you can try swapping that rectifer with a Radio Shack $3 full wave rectifier module (good for 25 amps)

just transfer the alternator leads to the ac pins,,,, ground the neg. pin and the 12 volt positive pin is your output to the +12 v distribution.
 
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