1964 evinrude fisherman 5.5 running poor!

[caden1010]

I have a 1964 evinrude fisherman 5.5 and It will not run properly. I give it full throttle and it will only run about 5 mph. I cleaned the carb and the same problem persist. While out on the water I put the outboard in neutral and revved it to the sky for a couple seconds and then it started to clear up and ran great the whole time I was on the throttle. But I let off and came to a stop and went to get back on it again and I had the same problem. I am quite confused, could it be the spark plugs maybe? Any tips will help! Thanks I’m advance.

 

[jimmbo]

Keep revving it to the Sky and soon, you won't have to worry about it any more.
Basics..
Compression Test
Can it produce a Spark strong enough to jump a 5/16 gap?
Are the plugs Clean, and gapped at 0.030"?
The carb might need a good cleaning, Float setting checked/adjusted

My had one of these engines, in the 70s and 80s. It suffered lots of Abuse, was overheated, a few times, was submerged when I flipped a boat, ran without oil in the Gear Case.

 

[racerone]

How did it run for you last season ?-----Inspection / testing will help you.-----Do the above.------And consider water in the fuel.-----Slip clutch below the water pump could be a issue ( binding ) and robbing power.-----If you just bought it , you need to install a new impeller as well.----Check thermostat as they are often stuck open or missing.----The factory head gasket was a poor design.-----Replacement ( sierra ) gasket is better.

 

[lindy46]

May be running on one cylinder, or one cylinder intermittently cutting out. Try pulling plug wire one at a time. For example, if it dies when you pull the top wire, then the bottom cylinder is cutting out.

 

[oldboat1]

^^agree with the above responses. What was your carb cleaning procedure?