Explain to me, in simple terms..

[thepetrolist]

..what kind of symptoms an air leak in the fuel supply system would cause?

I think I have an air leak in both my 6 hp Evinrudes and in my 9.5 hps Johnsons fuel delivery system.. I suspect a bad connector somewhere between the tank and the connector on the engine.

The engines need lots of throttle to start, keeps the revs up fine for a moment but then dies instantly. They hardly idle at all. If they run long enough that I’m able to rev it up, the acceperation is really sluggish, they hesitate and sputter and sometimes even backfire! No, not lean sneeze, but a traditional backfire.
I have set the points correctly, the coils and condensers are fine, the spark plug wires are hooked up correctly.

I have cleaned the carbs, replaced the fuel lines in the engine compartment, checked and assured good spark, they have good compression. Theorethically, they have all they need to run. I use fresh gas and run them in a barrel.

I know that checking for air leaks is relatively straight forward, but I really hate dealing with these kinds of problems, and to be honest, I’m too tired to even bother at the moment so therefore I’m turning to you guys!

[1946zephyr]

Are you using the same tank on both motors? If so, I would try a different tank.

If that solves the issue, then I would go through your tank and make sure there are no restrictions in it.

[fleetwin]

An air leak in the fuel inlet section (suction side) would most likely give similar symptoms to a weak fuel pump. The engine would run for a few minutes, then stall out, you would need to pump up the fuel bulb in order to fill the carb and get it running again.
Usually, an air leak would show up as a fuel leak when the fuel bulb is pumped up, except if the air leak was before the fuel bulb.
So, I’m thinking that if your engine has an air leak in the fuel system, you could probably make it run OK by squeezing the primer bulb constantly.
Like 46Z says, trying a different tank might give some good information. And, my advice/descriptions apply to an air leak, not a fuel restriction.
Your symptoms really don’t seem like those from an air leak, and it is unlikely that both your engines have an air leak, unless the problem is tank related. Is your fuel/oil supply fresh? Any water in the tank?

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