weird tach problem

[lkrasner]

I can not figure out what the heck is going on. My tach seems to be accurate at idle. as I increase throttle it goes up slowly as normal. at about 1/8 throttle it changes directions and goes down to 0 as I accelerate very quickly. What the heck is going on??!!?! this is driving me insane, so I hope someone has an idea of what is going on.

 

[metriccrescentwrench]

Re: weird tach problem

You didn't mention what engine you have, but anyway...... I'd be a case of my favorite beverage that you have a bad rectifier. I'd also bet that if you monitor the battery voltage it's not charging the way it should be.

 

[lkrasner]

Re: weird tach problem

Johnson 115 1995. and what the hell is a bad rectifier? i sort of know what a rectifier is in an electronics sense, but can you give me a little more info. Battery charging is possibly a problem. They charge but always seem weak, and if I take a bunch of short trips, i have to hook up the charger. Is this rectifier replaceable? if so how much would it cost? also, how is the charging related to this. Thanks in advance, and sorry to sound like an idiot!

 

[Will Bark]

Re: weird tach problem

Rectifier is a unit that changes AC voltage to DC voltage and charges your battery as well as sending the pulses to your tach. Go to www.marineengine.com and look up your enfine by year and model # in electrccal section. Good luck Your unit may be partially under the flywheel.

 

[metriccrescentwrench]

Re: weird tach problem

In this diagram the rectifier is #46 (it's shown in the "ignition" section and not "electrical". You can also find the part number which will come in handy for crossing it to an aftermarket (and less expensive) part.

http://shop2.evinrude.com/Index.aspx?s1=sr6uadmcic28vpt1vbdb09lo20&catalog_id=0&siteid=1

EDIT: well, the link to shop2.evinrude.com doesn't work the way it used to. You'll need to drill down to find your model, then go to the ignition section.

 

[lkrasner]

Re: weird tach problem

Is there any chance that a local boat repair shop would have a rectifier/ regulator? I found it in my engine, and there is nothing obvious wrong, but I wouldn't expect there to be. It was not under the flywheel at all, just under a plastic cover, and very easy to get at with just a few screws. Found it by total luck though. I was taking off the plastic to get to the flywheel so I could take that off and the part number caught my eye. The only after market I can find is CDI 193-4847. which is still $130 or more.