Gas Line

[rogerschwake]

  Had my 4HP 1986 Johnson outboard sputter and stop running this weekend. Checked the fuel line and the primer bulb was hard. Removed the fuel line from the engine and only could get a few drops of fuel to come out when I pushed in on the check ball at that end of the fuel line. Tried this 3 or 4 times with no change. My fuel line has quick disconnects on both ends so I reversed the line and pumped the primer ball and I think the fuel in the line pumped back into the tank. After reversing the fuel line and pumping up the ball the engine ran good for another hour. I don't know if there was something blocking the line or some kind of vapor lock? Anyone have an idea what happened?
ROGER

[Salty19]

Could of been vapor lock, yes.

Could also be excess pressure in tank which would raise gas levels in the carburetor float bowl and cause flooding.  If the tank is full and the sun is beating on it with the vent valve closed or barely open enough pressure could buildup to force excess gas through the tube and past the float pin, which moves up and down with fuel levels in the carb to regulate the flow internal to the carb. In the ideal situation, only enough gas is let in that is being output into the engine, which would keep the level consistent. This fuel level plays a big role in the lean/rich mixture equation.  Too much fuel, too rich, and it will stall with more smoke and have a deeper sound, sort of like a steam engine chug sound.  Too little fuel, too lean and it will not smoke as much, might have a slight burning smell and sounds more metallic/tinny.

If, when you got it started again it smoked more than usual for a moment or two, you basically flooded it, and since 2 strokes will draw this oil/gas mixture into the crankcase first before combustion, sometimes it can be flooded worse than initially thought.

If no smoke, I bet it was vapor lock.   I had this problem on occasion with an old chainsaw. I think what happened is it was running lean and hot, when I stopped the motor for a break (sawing logs is hard work!), it would heat up the fuel and be very tough to restart.  But if I drained the carb it would fire right up. I recall from a conversation with a local lawn/garden shop that using winter blended gas in hot weather might cause this to occur too.

Check and clean the spark plug in case it got too rich.  Those deposits if left unchecked will buildup and make it difficult to start or only run at higher rpms.

Used to have that motor...it ran sweet...I would like to have another one if I can get my hands on one.