1978 merc 65hp questions

jbjennings

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Joined
Jul 18, 2007
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3,903
Guys,
I've got myself a pontoon barge and it came with a '73 or '75 merc 65---the 3cylinder/2 carb. version. I was wondering if anyone had any opinions on this thing. It fires up easy when warm--just a touch of the key. But it idles rough and gradually leans out and then dies. I'm suspecting fuel pump but it's been sitting for a while and although I'm absolutely dreading it, am going to clean the carbs. Could dirty carbs/ sticky float valve be causing this? I can easily squeeze the primer bulb when running and it will slow down and idle, although pretty rough, and as long as I give it fuel with the primer bulb, it will continue running. What do you think? Also, the fuel pump looks like it is in combination with some kind of water pump mechanism. Is this some kind of fuel heating device???? One more thing....the compression is 140, 140, and 145lbs. on the top. I'm thinking this is darned good.
Any ideas would be very helpful.
Here's a pic of it.
 

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jbjennings

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Joined
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Re: 1978 merc 65hp questions

One more thing---it has NGK surface-gap plugs. I'm thinking this is a no-no. What kind of plugs should it have?
Thanks again,
JBJ
 
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