1980 Mercury 4 cyl 80hp rectifier screw up

[ricohman]

I bought my first boat today and I'm pretty exited about it.
But I think I may have screwed up the rectifier. When the owner told me about the battery needing to be charged once in a while I figured the charging system may not be working.
So I disconnected the battery (motor continued to run) to test it. I have read this is a good way to kill a rectifier. :facepalm:The motor continued to run with or without the battery which was disconnected for a few seconds. Starts up instantly regardless.
I don't pick up the boat for 2 days but I'm now thinking I should bring a rectifier with me as I most likely killed the one in the motor. I'm quite embarrased about this as I am an auto mechanic.
When I get the boat home I am going to put a voltmeter across the terminals and see exactly what's going on but since the boat is beside the lake I wanted to take it out for the day, which is why I wanted to take along a rectifier.
Anyway, is the rectifier buried deep inside the motor?

 

[ricohman]

Re: 1980 Mercury 4 cyl 80hp rectifier screw up

This forum has so much great info.
I think I may or may not have screwed the rectifier but by bypassing the two yellow leads I can run the boat anyway, so my day is still salvagable.
It's not much of a first boat (1979 Starcraft open bow trihull) but it will get me on the water so I can float around and do some fishing in these Saskatchewan lakes.

 

[j_martin]

Re: 1980 Mercury 4 cyl 80hp rectifier screw up

Learn from your mistakes. Don't go on what you hear unless you understand the topic. If you can't find the rectifier in your motor, you obviously don't know much about the topic.

Before you buy anything, put a voltmeter on the battery and see if it's being charged. In good shape, it should be a little over 12V with the engine off. Engine running, it should be over 13V, and higher when the engine is revved. You can do this when you first get to the boat, and if it isn't charging, tape off one of the yellow leads to prevent damage to the stator. BTW, if it has a tachometer on it, and it's working, the charging system is working.

It won't hurt anything to run for a few hours if the rectifier is bad, as long as you keep the battery up by recharging it between use. Unless you're constantly starting and stopping the engine, or constantly trimming it, the battery should run for a day. If you take anything along, take a pair of jumper cables.

 

[ricohman]

Re: 1980 Mercury 4 cyl 80hp rectifier screw up

Learn from your mistakes. Don't go on what you hear unless you understand the topic. If you can't find the rectifier in your motor, you obviously don't know much about the topic.

Before you buy anything, put a voltmeter on the battery and see if it's being charged. In good shape, it should be a little over 12V with the engine off. Engine running, it should be over 13V, and higher when the engine is revved. You can do this when you first get to the boat, and if it isn't charging, tape off one of the yellow leads to prevent damage to the stator. BTW, if it has a tachometer on it, and it's working, the charging system is working.

It won't hurt anything to run for a few hours if the rectifier is bad, as long as you keep the battery up by recharging it between use. Unless you're constantly starting and stopping the engine, or constantly trimming it, the battery should run for a day. If you take anything along, take a pair of jumper cables.

Thanks for the advice. I don't have the motor here so thats why I'm asking if the rectifier is buried and I thought I would test it and swap it out if its easy to access. I don't want to damage anything for a test run so maybe I will just bring the boat home and make sure its ok.
Will this outboard continue to run with a bad stator, regulator or rectifier?

 

[ricohman]

Re: 1980 Mercury 4 cyl 80hp rectifier screw up

Swapped the new rectifier on after the old one tested bad. The battery is low on charge at 12.3 volts and slightly less running.
At idle its now about 12.7 to 12.8 volts but a bump of the throttle and its over 13 volts.
I won't be doing that stupid trick again.