Re: Govenor problem fixed

Posted by Janicholson on August 04, 2005 at 06:33:35 from (199.17.6.77):

In Reply to: Govenor problem fixed posted by Mels on August 03, 2005 at 13:52:49:

The float is probably not the problem, but it is at the heart of the situation. as on the toilet tank in the batho\room, the float is the shutoff controller for fuel (as it is for water in the toilet tank. Both floats control a valve that actually shuts off the fluid flow. In your carb, there is a needle valve that is attached to the pivot end of the mechanism. this valve consists of a metal moving needle (usually triangular, or square to allow fuel to flow) with a conical point on the upper end. The seat for the needle is screwed into the upper carb body.
The needle (originally) was metal and pushed into the brass seat to stop fuel flow. the touch point for the needle and seat can be described as a thin ring of contact. This ring of contact was (when new) less than .003" across the surface of contact. The pressure of the float lifting the needle shut off the fuel easily.
After years of wear, the needle and seat both wear to the point that the contact area becomes as much as .030" wide. They are then much more prone to leak due to minor normal misalignment, and to trap foreign particles inbetween the flatter surface. New needles and seat combos use a synthetic rubber like compound on the tip of the needle (called "Viton") to seal the entry to the carb when the float is up.
HOWEVER !!! even a new Viton tipped needle and seat won't seal the entry when particles of scale/rust/hair/twigs/and the like wedge under them. A screen is (supposed to be) located in the carb inlet fitting to stop junk from entering. it can work, if it is there. It may not trap all particles capable of causing leaks at the needle/seat. The sediment bowl, screen in the sediment bowl, and screen/stand tube in the tank are all potential areas of concern for stopping your problem. Use a funnel with a coffee filter to drain the fuel into (appropriate) clean fuel cans. Then in an open area, with the battery removed, and rags to clean up the spill, remove the sediment bowl from the tank. !!!be careful to apply even pressure and turn lefty loosy to get it out. It is zink (pot metal) and easy to break off if bent over as it is turned. clean all these components carefully. Look into the tank and check for crud. clean all crud from the tank. (see cleaning gas tanks in these archives)
With a new needle and seat, and a clean system, there will be no more fuel leak at the carb. Continue to shut off the fuel when stopped for the day.
Best of effort will cure it pronto.
Jim Nicholson

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