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fuel issues???

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nicknack2

Regular Contributor
Me and my buddy are working on his 2000 50 HP Mercury, the problem with the motor is that it will start and the after a few minutes will die out, we clean all three carbs, checked fuel pressure and everything checks good, also changed the fuel filter just in case, any ideas?:confused:
 
Did you try pumping the fuel bulb when you get it running.

It initally sounds like either, you have an air leak somewhere in the lines between the tank and the motor OR the fuel pump diaphram is shot.

When you first pump it up you fill the carb bowl. If the fuel pump is shot, once it drains the bowl (and no more fuel is being pumped in) she dies.

If you can manually pump it (keep squeezing the bulb) that would pretty well prove the fuel pump is shot...
 
Thanks Galam, I tried pumping the bulb, but it does the same thing, the bulb stays hard, the pump has about 7 PSIs so I ruled out the pump, I was thinking the needles and floats but separated the bowl from the body and saw fuel coming in thru the needle as I pumped the bulb, I know that it looks like a pump issue, but the fuel pressure is there :(
 
Are you getting any fuel coming out of the carb throat or does the float valve seem to be working when you pump her up?

(should have added) Alternately, is it possible the float is sticking in the (up) position keeping the needle valve closed in the seat such that it's not letting anymore fuel into the bowl?

Since the fuel is making it through the valve seat with bowl separated that rules out a clog there, but it doesn't mean that when the needle is in the seat that it moving to allow the fuel to pass (deformed or slipped off the tang that holds it to the float?).
 
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you mean as if the float valve was stuck open???, no i dont think is stuck open to me it seems like if it is starving for fuel, so you think it might be chocking???
 
I was thinking more "stuck closed" - you pump it up and fill the carb bowl and then the needle sticks in the seat blocking further fuel supply.

Once the bowl is empty of it's initial dose of gas the motor dies because the carb is "empty"...
 
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