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40 hp Merc troubleshot- need advice

D

David W.

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Newbee poster, hope i am in right place. History:Have a 1992 40hp 4 cylinder Mercury. About 4 years ago I swapped batteries with engine running and apparently melted some stuff. Took it to a repair shop and he replaced stater, wire harness and rectifier. I don"t think he replaced switchbox but at 73 my memory is fading. He installed a red stater and adapter box. About that time I noticed my volt meter pegging at 16 volts on plane. I replaced the rectifier again, no help. I was assured my new depth finder had a high volt shutdown. I held my breath for 4 years. NOW. first trip this year, no fire at spark plugs. decided to attempt fix myself so ordered DVA and downloaded 3 troubleshooting procedures, all were different. Called mercury factory (rep said this engine was before his time??) and DVA maker said he just did not know if this engine was capacitive discharge ignition or ADM.(checkout is different). troubleshot it down to switch box. Now I need help on 3 questions.
1. Can I just replace the rectifier wit a later model regulator/rectifier?
2. It seems the conventional wisdom says if yo think the switchbox is bad you need to troubleshoot more. Is that right?
3. anyone know if this engine is CDI or ADI.
 
1. Can I just replace the rectifier wit a later model regulator/rectifier?

I've used a bunch of unrelated rectifier/ diodes with little differences. You can also (and better yet) buy a CDI voltage regulator that does the job without messing up your tach.

2. It seems the conventional wisdom says if you think the switchbox is bad you need to troubleshoot more. Is that right?

You can check everything out with a DVA meter set on DC. While someone cranks her over, check all the connections as discussed in the CDI troubleshooting manual that you can download free off the Internet. The motor does NOT have to be running to do this.

And shame on a Merc rep saying your motor was too old to help you. Jerk!

Jeff
 
cannot for the life of me figure out loading a picture! Read and reread instructions, my computer said picture was uploading but can't find the "manage attachments on new post page per instructions. Don't give up on me, i am working on it.
 
Loading pictures: Untitled-1.jpgUntitled-2.jpgUntitled-3.jpg size (less than 200kb, say 185k)
 
I usually get away with up to 1000KB, but usually go 800.
Note to Jeff....perhaps that Merc rep was too "young" to help Dave.....eh?
 
Why is it, the older we get, the more knowledge we accumulate? But then our physical capacity has already started the downswing. Guess we are at our peak, when those 2 graphs cross.
 
My crossed a loooong time ago!

Jeff

PS: Pennsylvania Dutch (actually German) expression: Too soon old, too late smart!
 
Ha....I'm German too...mom's maiden name Davitshoffer, they changed it at Ellis Island to Davidsaver.
 
Maybe you'd be interested in the virus deaths "im Deutschland"-17_1586203675183.jpg the Germanic Volk seem to be on the ball.
 
Last edited:
Artie Johnson! Been a while.

My father's original name was Pereira--it's Portuguese. The Ellis Is. drones changed it to Perry.

Jeff

PS" It was actually "Vvvverrrryy IN-teresting!"
 
EXACTLY, you got me laugh - in! Perry is a great name, strong and simple.
David, you'll have to ask your 6 year old granddaughter to post those photos for you.
 
Any time my wife or I can't figure out how use our I-phone, I call my grand kids and they ALWAYS know what to do!

Embarrassing.

Jeff
 
It's good for the children too. Seems when we were young, we couldn't demonstrate ANY knowledge over and above our parents or seniors.....new times, Jeff, new times.
 
If anyone gets down this far, I finally jumped in and replaced the switch box, that fixed the problem! so for question 1. no answer. Q2. False and Q3 Thanks racerone.
 
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