1977 115 hp Johnson Increase the throttle the engine cuts off

[saltwaterbluefish]

I have a 1977 115 hp johnson outboard. A classic i know..lol.. I was hoping someone could help me with an issue i keep having. After I crank up and let her idle for 5 minutes, when I try to go to full throttle the engine cuts off or seems like she isn't getting enough gas. I usually put her back to a lower speed (5 mph), puddle for a little longer, and then she usually will allow me to go at WOT without cutting out. While she is idling she doesn't sound rough, so i don't think it is a carb issue.

Last time I took it to the mechanic he didn't seem that concerned, but did not want to really explain why it was doing that. The compression on the cylinders were all around 10of each other and I just replaced the fuel lines and tank.

Any thoughts or suggestions would be appreciated

 

[Coachjfk]

Re: 1977 115 hp Johnson Increase the throttle the engine cuts off

I have the 76 model 115hp. When I first got the boat, I had this same problem. Rebuilding the carbs and replacing the fuel lines seems to have solved this for me.

I believe that my (system) was sucking air. The hoses seeped a little gas when pumping the ball and a few of the bolts were a little loose holding the carbs to the engine.

 

[saltwaterbluefish]

Re: 1977 115 hp Johnson Increase the throttle the engine cuts off

I see a little bit of gas leaking also after choking. Are your fuel line secured with zip ties or hose clamps?

 

[oldrudedude]

Re: 1977 115 hp Johnson Increase the throttle the engine cuts off

Drain the carb float bowls and see what comes out. A little water at the bottom of the bowl can surge up into the high speed jet on hard acceleration.

 

[Daviet]

Re: 1977 115 hp Johnson Increase the throttle the engine cuts off

While you have the bowl drains out, check the high speed orifices for being plugged or restricted.

 

[Coachjfk]

Re: 1977 115 hp Johnson Increase the throttle the engine cuts off

I see a little bit of gas leaking also after choking. Are your fuel line secured with zip ties or hose clamps?

Mine are secured with clamps. Quality of hoses is important too. Works better when they (hoses) are still supple.

Where do you see the gas leaking... from the hose connectors? Try tightening or double clamping has been recommended previously on the forum.

 

[saltwaterbluefish]

Re: 1977 115 hp Johnson Increase the throttle the engine cuts off

Thanks for the ideas. I'll give the motor a check tomm.

I think the first thing I will do is to switch the zip ties the mechanic put on for clamps. Everytime I push against the fuel hoses that are after the fuel pump I see little drops of gas. I actually was dropping alot of gas from that same spot when I took it too him and that is when he rebuilt the carbs.

May be time to look for a new mechanic or learn myself.

 

[oldrudedude]

Re: 1977 115 hp Johnson Increase the throttle the engine cuts off

The fuel lines after the fuel pump are under pressure and will not suck air. Clamp your hoses but do as daviet suggests.