Test Rectifier

[dstuard]

Is there any way to test the rectifier on my 115 hp mercury (1983)? I put one on yesterday that I thought was good just to see if the rectifier could be my problem and it started blowing the fuse to the starter. Is there any way to test and make sure the one I have is good?

 

[Jerry M.]

Re: Test Rectifier

Try this: disconnect the battery cables from the battery. Disconnect all leads from the rectifier.<br /> <br />Connect the positive lead of an ohmeter to ground of the rectifier and the negative lead to each stator terminal alternately. You should have continuity.<br /><br />Connect The negative lead to the ground of the rec. and positive to the stator terms. Should have no continuity.<br /><br />Then connect the negative of the ohmeter to the positive terminal of the rectifier and the positive alternately to each of the stator terminals. You should read continuity. <br /><br />Then connect the positive ohmeter lead to the positve rectifier terminal and negative to each of the stator terminals. Should read no continuity.<br /><br />Jerry

 

[NathanY]

Re: Test Rectifier

If it does turn out to be a rectifier problem, a new rectifier is only $36.00. Probably better to replace it anyway, with all the trouble that you have been having.

 

[dstuard]

Re: Test Rectifier

OK I did the test. Black to ground and red to terminals 1 of 2 gave continuity. Same one did on red to ground and black to terminals. With the black to + terminal on rectifier I got no continuity to either one. With red to + side neither terminal gave continuity. The last one was the only one that came out like you said. Looks like I need a new rectifier. Could this cause a bog down and miss at WOT? I did the test several times to make sure. Does it look like I need a new one? Could this be caused or have caused stator problems?

 

[dstuard]

Re: Test Rectifier

Any ideas Gone Fishin?

 

[dstuard]

Re: Test Rectifier

^^^

 

[Hooty]

Re: Test Rectifier

Have a look at this<br /><br /> Rectifier And Spark <br /><br />c/6<br /><br />Hooty

 

[Jerry M.]

Re: Test Rectifier

A good way to tell if you have a bad rectifier is wether or not you have a reading on you voltmeter when your motor is running.. If the rectifier is dead, I think your voltmeter showing output will be the charge remaining in your battery. I'm not a mechanic, but I know your motor will run without a rectifier until you wear down your battery. I have a Merc, and mine does (did).<br /><br />Jerry

 

[dstuard]

Re: Test Rectifier

Hooty- I am not sure you posted the right page. All I saw was tach talk.

 

[Hooty]

Re: Test Rectifier

Damn!<br />O-k, here it is.<br /><br />This is topic Mercury Rectifier failure in forum Outboard Engine Troubles & Questions at iboats Boating Forums.<br /><br />To visit this topic, use this URL:<br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=17;t=020827 <br /><br />--------------------------------------------------------------------------------<br />Posted by No Spark/No Ducks (Member # 17320) on October 14, 2002, 02:09 PM: <br /> <br />If a rectifier fails the Ohm test would it keep the ignition from firing?? My merc 40hp will not fire, and the rectifier doesn't pass all the ohm tests. The Stator and Trigger coil check out OK. But the switch box still has me guessing. Any help would be great!! <br /> <br />--------------------------------------------------------------------------------<br />Posted by schematic (Member # 4724) on October 14, 2002, 02:15 PM: <br /> <br />In some cases, a shorted rectifier can cause high magnetic flux under the flywheel and raise havoc with the charge/trigger coils. Disconnect all wires from the rectifier to see if the spark returns. If it doesn't, its not rectifier related.... <br /> <br />--------------------------------------------------------------------------------<br /><br />c/6<br /><br />Hooty

 

[dstuard]

Re: Test Rectifier

Thanks Hooty. I am going to buy a rectifier and stator today. My stator ohm test came out 6900 where it was supposed to be 6200 so I am going to give that a try if I can get the fly wheel off.

 

[dstuard]

Re: Test Rectifier

Got my stator off and did an ohm check on it. Red to blue was 7200 off the motor. I am pretty sure this will be my problem. I will let you know tomorrow after school. Educting kids must come first. I think I will replace the rectifier just to be safe. I should get the same result from both terminals oppisite the + shouldn't I?

 

[dstuard]

Re: Test Rectifier

New rectifier and stator are on. Ran on the muffs and I can already tell a big difference. It will actually rev up now. Hopefully it is not just wishfull thinking. Camping trip with the family this weekend should tell all.

 

[dstuard]

Re: Test Rectifier

Those of you that are tired of seeing me post will be happy. After replacing the stator and rectifier she ran like a bat outta hades. I really did not realize how much power I had. Now it will be time to tackle the water in the lower unit but that will have to wait a while. I would like to thank everyone for their help. Without you guys I would have given up and sold it. Good thing is I got a fish and ski 83 Glastron with a 115 Merc of the same year for 750.00. Put about 400.00 more in so I feel like I made out like a bandit.