sticking needle valves in carbs

[reynold460]

have a 1984 mariner 115 hp with the side bowl floats .had the needle and seats replaced and when i would blow air into the fuel inlet (by mouth only) could hardly pop the needle off the seat and the needle and seat are new is this normal being that i know the fuel pump only puts out around 3 lbs of pressure i cant see how the needles arent going to stick does someone have a answer to fix this . . .the reason why i replaced them is the motor would die out and when i would apply very hard pressure to the bulb it would run ok ffor a bit then die down again until the bulb was pressed again the fuel pump is new . i have pretty much narrowed this down to the needle valves after taking this to 3 different boat shops and they were all telling me it was electrical issues to find out after replacing the stator,switch boxes,fuel pump,fuel lines,it was still the same

 

[1nebel0]

Re: sticking needle valves in carbs

It is a fuel problem as when you force fuel into the carbs it will run...I have not seen needles sticking where air wouldn't move them..As you said 3-5 lbs is all the fuel pump will put out...Are the floats set correctly...I am getting ready to rebuild carbs on a 1985 I just picked up... I will only buy the gasket kits for the three carbs as rarely do you need to change the needles and seats... Why were they changed as that kit is much more money if you have all three carbs rebuilt by a shop given the current shop rates...I won't get to my carb job until next week so good luck..Lastly if the float are not plastic, they can get saturated and they become to heavy to float however that would cause the opposite of your problem as the engine would be flooding....Let's see what others have to say..

 

[j_martin]

Re: sticking needle valves in carbs

Very hard pressure on the bulb will overcome normal needle and seat valves.

You have much more wrong with the carbs than the needle and seat. I suspect that jets and passages are clogged up to the point that the only way to get fuel through them is to overcome the needle valves and flood over the float chamber. About the same effect as spraying fuel into the carb throats. Very nasty mess indeed.

If the new needles are sticking, you're getting some kind of sticky debris into the carbs through the fuel system. Fuel contamination, rubber from hoses, resin from old fiberglass tank..........

I suspect, however, that your testing method is not up to par. If the carb is in a normal attitude, fuel in the bowl would hold the needle to about 7 lbs pressure, and there should be no resistance at all if the float bowl is empty. Inverted, float weight is the determining factor, and totally unreliable as a measure of performance.

hope it helps
John