Rectifier ???

[fly4fish]

I have a simple question and i hope i answered it lol. First thing is i have been rebuilding a 77 silverline with a 1400 ob merc. I cleaned all three carbs, new stator, new plugs, wires, new dist cap, new battery, new internal wire harness and external wire harness. has good compression... the prob i am been getting is ill hit the lake with fresh charged batteries and she fires up great, idles like a merc, planes out great, runs awesome, and heres my headache the more i turn the motor on and off the harder it gets to start and when it does start it has no power. it doesnt want to plane out. I thought about it while stuck in the middle of the lake and was wondering if the rectifier is not allowing the batteries to get charged? and if so does that mean im not getting a strong spark and also is it that the reason way it has no power to get out of the hole?

(weak spark+hard starting+no power+low batteries=bad rectifier)???????

any ideas help, thinking about trading for a paddle boat but my legs might cramp up and id be in the same perdicament lol.

 

[orangeman]

Re: Rectifier ???

With the boat running check the voltage across the battery. It should be higher than with the engine off on mine it goes from 12.5V to over 13. If the voltage isn't higher your not charging the battery and rectifier could be bad or you have some bad wiring. If your tach is dead also it's probably a bad rectifier. I don't think the rectifier has any impact on how it runs once started.

 

[Joe_the_boatman]

Re: Rectifier ???

I agree with the above, the rectifier's job is to charge the battery. The good news is, at least on my Merc, a brand new rectifier can be had for about $5 from Radio Shack. Or, you can spend $30 on an OEM part. I heard they do go out occasionally.

 

[Chris1956]

Re: Rectifier ???

Fly On those dissy ignition Mercs the stator and rectifier only charge the battery. They have no effect on the spark. The ignition system requires 11VDC or more. Get yourself a new rectifier and repair the charging system and see if your issue goes away.

 

[fly4fish]

Re: Rectifier ???

how does one explain when i check the spark with a spark tester it shows a dim light when the battery is really low and after i charge the battery to full charge the light in the spark tester is really bright? these motors are so simple yet they can drive a man nuts cause of little simple problems?

 

[sschefer]

Re: Rectifier ???

What does your rectifier look like, does it have terminals or permanent wires.

 

[Chris1956]

Re: Rectifier ???

Fly, You will have a weak spark when the battery is low, since it supplies all the power for the ign system. Fix the charging system so the battery will stay fully charged.

 

[sschefer]

Re: Rectifier ???

This is a really basic system. Since the engine is sucking the life out of your battery this indicates a problem with the alternator/stator in that it is not getting it's output to the charging circuit. Since you have recently replaced your stator, the next weak link is the rectifier. You can test the charging circuit by simply starting the engine and reading the voltage at the battery. It should read somewhere around 13-14 volts if the charging system is working. If you're not seeing this voltage but instead reading 12.5 or less, then first get a manual and check all your wiring just to make sure you wired the new stator in correctly. If all that is good then replace the rectifier and you should be back in business.

By the way, if the stator and rectifier are in good condition the motor should pull start and run without the battery.

 

[cell]

Re: Rectifier ???

You might need to bump the throttle up a little to see it go above 12.5 volts....

 

[fly4fish]

Re: Rectifier ???

Thanks guys, the rectifier tested good but the three terminal studs were rusted and stripped. (not a good contact ) i replaced it with a new one today so now i gotta wait till its nice to try it out. Thanks agian.