1979 40 hp electric start merc rectifier repeatedly burns out

[chuckwebster]

My motor started running rough and then would not start. About a week later while sitting in the driveway, there was a whole the size of my finger in the rectifier. I replaced the rectifier and while testing it in the driveway for about 15 minutes it ran fine. The next time I started it, it started rough and ran like it was missing and then would not start at all again. I tested the rectifier with an ohm meter and it tells me the rectifier is bad. Why does it continuously burn out?

 

[WillyBWright]

Re: 1979 40 hp electric start merc rectifier repeatedly burns out

Unless you have amplified battery ignition, a blown rectifier should have nothing to do with running quality. I don't think that old 40 had that type of ignition. Are your wires crossed somewhere?<br /><br />Rectifiers blow from reverse polarity at the battery, loose and/or corroded battery connections, or loose and/or corroded rectifier connections (Including how it grounds). Sometimes a bad battery can take one out. That should about cover the possibilities.

 

[Clams Canino]

Re: 1979 40 hp electric start merc rectifier repeatedly burns out

Ya,<br /><br />Make sure next time you start with a fully charged battery before you replace the recifier. A nearly dead battery looks like a dead short to a rectifier.<br /><br />-W (popped a couple that way)

 

[chuckwebster]

Re: 1979 40 hp electric start merc rectifier repeatedly burns out

A new battery did the trick. Thank you.

 

[Clams Canino]

Re: 1979 40 hp electric start merc rectifier repeatedly burns out

/grabs Willy and does the Snoopy dance. <br /><br />

Originally posted by chuckw:<br />A new battery did the trick. Thank you.