Help with old evinrude

[Barkerbob]

friend has a 1972 evinrude 100 on a pontoon boat. It started having a running issue. First five minutes or so runs great then shuts off like you turned key off. Starts right back up but runs like it’s half throttle until it shuts off again. Eventually it will shut off and not restart for a while. He sent it to a local who has put on fuel pump, rebuilt carbs, new coils and new power pack. Still has same problem. My friend has been out a lot of money. I am feeling this is an electrical problem with something getting hot and shutting it down. Not sure why the immediate restart until it does it a few times the. You have to let it sit a while. Any ideas on where to start would be appreciated.

 

[racerone]

Pull flywheel.-----Clean rotor.---Check anti-reversing spring.----Clean distributor cap.-----Use timing light to see if you can pinpoint which cylinder is loosing spark.---Perhaps run at night and look for sparks jumping to flywheel.-----Does it still have the " clipper circuit " installed " on it.--You have replaced the water pump impeller I hope.

 

[Barkerbob]

Pretty sure they did not replace the impeller. Not sure what a clipper circuit is.

 

[Barkerbob]

Pretty sure they did not replace the impeller. Not sure what a clipper circuit is

Pretty sure they did not replace the impeller. Not sure what a clipper circuit is.

when it stops it’s like you turned the key off. If it was just one cylinder losing spark I would think it would just start missing correct?

 

[F_R]

That battery CD system was state of the art in 1972. Can be a PITA for today's techs who do not understand it and just start replacing parts. There are any number of possible faults. Worse, the factory service manual describes troubleshooting with an obsolete tester.

Got any old grey-haired techs in your area?

 

[racerone]

I think they already spent about $1000 with no results.-----Your location ?-----I met a fellow one time who was trying to keep a similar motor ( his late father's ) going.----At an AOMCI meet.----Was hoping / looking for contacts to help him.----He was shocked by the $550 tab for cleaning the carburetors.

 

[Faztbullet]

Need to check voltage when running...if overcharging it will do this as internal parts overheat.

 

[Barkerbob]

I think they already spent about $1000 with no results.-----Your location ?-----I met a fellow one time who was trying to keep a similar motor ( his late father's ) going.----At an AOMCI meet.----Was hoping / looking for contacts to help him.----He was shocked by the $550 tab for cleaning the carburetors.

SW Indiana. Yes he has spent a bunch on it already.

 

[Barkerbob]

Need to check voltage when running...if overcharging it will do this as internal parts overheat.

Ok thanks. Where do we take the reading? At the battery?

 

[Gardog66]

I would pull a spark plug it will tell you so much if it’s really wet it’s flooding if it’s really dry it’s not getting enough fuel if it’s got a tan corona ring it’s perfect. It’s either a electrical problem or fuel. or a over heating problem. The gray wire should be a safety shutoff, you can disconnect to see if it’s that but beware you could over heat your engine. I always use a temp gun to see what the head temp is.

 

[F_R]

Um...isn't grey the tachometer lead?

 

[racerone]

Agreed---I thought grey was for tachometer in those days.----I do not believe there was a " safety shutoff " on a 1972 model 100 HP.----Testing the overheat warning horn on this 1972 model 100 HP might be a good idea.

 

[Gardog66]

Um...isn't grey the tachometer lead?

Yeah I think you’re correct the tan wire is the temp sensor I believe. I always refer to the manual because I have sometimers I can remember thing’s sometimes.

 

[racerone]

The temperature sensor just sounds the horn ( if it is working ) and it does not shut off the motor in case of overheat condition.

 

[Gardog66]

The temperature sensor just sounds the horn ( if it is working ) and it does not shut off the motor in case of overheat condition.

It is on the old side so I’m not so sure but I was thinking reading something in leroys rambling about the CD box came out in the early 70s with a over heating wire to slow down the engine? Correct me if I’m wrong

 

[racerone]

I believe you are wrong here.---I doubt leroy has information posted on these ignition systems on the V-4 of that era !

 

[Crosbyman]

fyi.... if it helps

 

[racerone]

Mastertecmarine----- shows the wiring diagram in color.

 

[Faztbullet]

You take readings at battery

 

[3rdtimesthecharm]

SW Indiana. Yes he has spent a bunch on it already.

I’m in Evansville. Don’t know if any local dealers with gray-haired mechanics though.