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Johnson 15HP Help please

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I have an 87? Johnson that will crank but dies if it's not at WOT and I keeping pulling the choke in and out. The motor seems to be running rich. It has set up for months and the Carb was just rebuilt. Anyone have any suggestions?

  • Super User

First you need to find out if it's fuel or ignition.  Use a spark checker on one of the plugs and make sure it's still firing when it dies.  You can also use a good timing light.

If it continues to fire as it's dying, then it's fuel.  Could be sucking air in a fuel line.  Pump the fuel bulb up tight and hold pressure on it, see if you have any leaks.  Trying running it and keep pumping the fuel bulb to see if that will keep it running.  Another check to see if it's getting fuel, when it dies, don't mess with anything and take one of the plugs out of the carb fuel bowl.  If only a very small amount of fuel drains out, it's not pumping fuel or the needles are sticking closed.

If firing,

Check for leaks that would let it suck air.

Make sure nothing is restricting the fuel line, from the tank pickup to the carbs.

Make sure fuel pump is pumping

If all that's good, clean the carbs and set the float level.

If it's flooding out from too much fuel, clean carbs, replace needle/seats and set float level.

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