1973 Mercury 65HP 650 HELP!!!

kelbone

Cadet
Joined
Aug 13, 2009
Messages
8
I am coming to you all again with a problem with this crazy motor..
It is about to be set on fire.. LOL.. We purchased this about 2 months ago and have had nothing but trouble from then.. The fella we got it from told us it worked great with a couple of things needing replaced.. Timing Belt & Impellor.. Well we changed those first off.. Wouldn't go any faster than 6 mph.. Re-set the timing, cleaned the carbs.. Tested it again.. Would go only 7 mph.. We started replacing things thinking they could be the problem..
Rebuilt Carbs, Re-placed fuel pump, re-placed fuel lines and water lines, New Plugs & Wires, All remainwires were replaced, New Coil, Tested Stator & Trigger... Tried it out again and it seems to want to go but when given a load it just won't get past 6-7 mph.. We then tested the switchbox per CDI testing and found that one of the wires was bad.. Just got the new switchbox yesterday.. Tested the boat at home did great as always.. Went to the lake to test and it does the exact same thing.. Nothing has changed at all replacing the switchbox.... We (Husband) and I are about to go nuts with this thing.. I say burn it but he is determined to get it running.. That is the the reason for getting it.. Trolling just isn't any fun when that is all you have..

The motor is 1973 Mercury 65Hp 650 on a 16 1/2 Fiberglass V-Hull.. Will this motor even plane on this size of boat? We are running out of things it could be after checking and replacing so much..

Thanks All Kelbone
 

corm

Lieutenant Junior Grade
Joined
May 12, 2000
Messages
1,241
Re: 1973 Mercury 65HP 650 HELP!!!

Hi,

Did you double check the timing belt to make sure it is in the right notch?
I would run it with the faceplate off and look at the carbs to see if they have the same fog of fuel going into the engine. With 2 carbs feeding 3 cylinders they can run like that on 1 carb. I am guessing you have spark on all 3 plugs.
Does one cylinder wash the plug? If so you may have a bad reed valve. That plug will be a different color than the other 2.

Another thing I have seen is that people do not get the 2 carb shafts hooked together so only the top carb opens up when you advance the control.
 

rodawg

Cadet
Joined
Sep 23, 2009
Messages
11
Re: 1973 Mercury 65HP 650 HELP!!!

I had the same problem and when I took the boat in for maintenance they told me that one cylinder was just sucking air because the spark plug threading was basically gone.
 
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