The mystery of the sinking float...

Dear Car Talk

Dear Car Talk | Jan 01, 1990

Dear Tom and Ray:

We have over 150,000 miles on our 1966 Plymouth Valiant. This car has always had excellent care, but has developed a dangerous problem over the last several years which our mechanic, Bud, has not been able to solve. As we approach a stop, or round a sharp corner, the car will die completely. This is very stressful due to the surrounding traffic. Our appreciation would know no bounds if you have a solution.

TOM: This is your lucky day, Eileen! Have you ever read "The Mystery of the Sinking Float?" Therein lies your answer.

RAY: Your carburetor has a float just like the one in your toilet bowl (except smaller). When the gasoline flowing into the carburetor raises the float to a certain level, the gas flow is shut off.

TOM: The problem with your float is that it's so porous and saturated that it's always on the verge of sinking. Any sudden movement--such as stopping or turning sharply--causes your float to go under. When that happens, the flow of gas is not cut off, and excess gas floods your engine.

RAY: Combustion requires a spark to ignite the gas. When too much gas comes in (when the engine floods), the spark literally gets drowned. In fact, if you listen closely when your car stalls, you can probably hear the little spark plugs crying "Help! Help! We're drowning!"

TOM: Tell Bud to scrounge up a new float for your carburetor and your troubles will be over. When he tells you he can't find a new float for this old beast, get him a whole new carburetor and say "this one's for you, Bud."

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