internal backfire

[austinmcelroy66]

I have a 1989 Yamaha 70etlf that keeps having an internal backfire. Any ideas why or what it could be?

[robert graham]

What you're calling an internal backfire may in fact be a lean sneeze caused by a lean fuel condition caused by dirty/plugged carb jets....have carbs ever been cleaned?....best to get this fixed before running the motor as a lean fuel condition can really damage the motor....

[99yam40]

Did you figure out what was blowing the fuse?
It would be nice for you to reply back to your other thread so others down the road can see what the problem was and how you fixed it.

What you are describing is what we call a lean sneeze.
Usually caused by plugging inside the carbs, but could be air leaks in gaskets

[austinmcelroy66]

the motors been sitting for 5 years so no i dont think they have been cleaned. ill try that and let you know what happens.