1976 Johnson Stinger 75 hp boggs down under load

[ShellsterT]

We recently purchased and old boat and motor. The owner said everything worked great. When he turned the motor over it popped right off. When the motor is in the water it idles great until you put it into gear, then it boggs down and dies. We have had the plugs changed, carbs cleaned, head gasket replaced and some other things. Everything has tested out great. Took it to the lake again. This time it doesn't completely die, but there isn't much power. What should we check/do next?

 

[Daviet]

Re: 1976 Johnson Stinger 75 hp boggs down under load

Have you checked the compression, what are the numbers?
Will the spark jump a 7/16" air gap and is it bright blue?
When the carbs were cleaned, were they completely disassembled or did some one just spray some cleaner into them?

 

[fireman57]

Re: 1976 Johnson Stinger 75 hp boggs down under load

Bump the choke when it starts to die. Seemed to be a common problem with this engine. Some people have rejetted the carbs and it helped. Do a search on 1976 75 hp and you will be surprised what you come up with. Oh, almost forgot. Welcome to iboats!