70hp missing badly

waterinthefuel

Commander
Joined
Nov 15, 2003
Messages
2,726
We took our old '79 70hp out fishing today and it idled like a new engine right at first. We fished, idling quite a bit, and by the end of the day it would die when putting it into gear. Even cranking the idle up to fast idle didn't help. If we could get it to finally catch and showered down on it, it ran pretty good until we fell of plane then back to the wild rough running. We had to paddle the boat onto the trailer, any hopes of idling up were gone. Plugs were as follows: 2 wet and 1 dry. What could be the problem? If it fowled the plugs, wouldn't they all be wet? Was it running on the one dry cylinder? Why did it have normal power at high throttle settings, and still showed plugs with differing results?
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: 70hp missing badly

After you make sure all cylinders have good spark, chances are all THREE carbs need to be disassembled, thoroughly cleaned, all passages blown out with air and reassembled with new kits. Then a link & sync procedure done followed by idle mixture settings. Idle passages are probably clogged with varnish and/or debris which is why it won't idle. High speed jets are larger and not current clogged.
 

waterinthefuel

Commander
Joined
Nov 15, 2003
Messages
2,726
Re: 70hp missing badly

Thanks, but the engine only has 2 carbs. We put new plugs in it and it runs like a new one. A 5 dollar fix, that's what I'm talking about!
 
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