after the motor dies I would immediately check to see if you still have a good fat spark, by grounding a spark plug and cranking the motor over, next I would check to see if you have fuel coming out of the squirters in the carb when you pump the carb. At least you will elimate spark and fuel problems. For an engine to run you need spark, fuel, air and compression. Next I would check your wiring out to make sure there is no conections that are not making a complete circuit or shorting out, causing you motor to shut down. If you find a problem with any of these situations you can look at the individual problem and work from there. Did you check to see if the exhaust Manifold Heat Control Valve on the passenger side exhaust manifold is stuck closed or partially closed? The manifold heat control valve assembly, (heat riser) is often overlooked as the source of low speed engine performance issues, which is a serious mistake. This simple device is essential for smooth engine operation, even in warm summer weather. The reason is simple physics; converting a liquid (gasoline) into a vapor (air/fuel mixture) requires the application of heat. Start your car on a cool day and watch the base of the carburetor; it will become frost-covered for a short period of time as the engine warms to operating temperature. The ambient temperature of air entering the engine will drop as latent heat within that air is consumed in the process of vaporizing droplets of liquid gasoline into the combustible air/fuel mixture. The manifold heat valve forces hot exhaust gases up around the base of the carburetor and the intake manifold plenum, (the central area directly under the carburetor) to warm the mixture. If additional heat is not supplied, the gasoline can easily condense back into a liquid as the air/fuel mixture comes in contact with the inner surfaces of the intake manifold. This “leans” the mixture causing rough idle, hesitation on acceleration and stalling. As the engine warms to operating temperature, less heat is required and the manifold heat valve swings open, allowing the exhaust gases to flow directly out into the exhaust pipe.
Starting a cold engine requires a very rich mixture for the very same reason. The manifold passages are so cold, the only way to get enough air/fuel mixture to each cylinder is by use of the carburetor choke. The majority of gasoline drawn into a cold engine condenses on the walls of the manifold and never reaches the cylinders to fuel the engine.
aboard Beckett!
