"Cranking" involves the starter making the engine turn over, which it sounds like is happening. A "no start" condition with normal cranking speed involves low compression, lack of fuel, or no spark. Since adding a squirt of fuel makes the engine start, I'm going to assume your compression and spark are adequate, if not perfect. Yod haven't mentioned if you have a manual or an automatic choke. If it's manual, do you know if the choke is closing all the way when you pull the knob? Check on that, as sometimes the choke plate will not move far enough to get enough restriction to the airflow. A choke operates by strangling off airflow at the top of the carburetor, and letting intake manifold vacuum be applied to all the fuel passages in the carb. The temporary very rich mixture allows enough fuel to reach the cylinders that at least some of it burns. Once the engine fires, release the choke slightly to avoid flooding, or over-rich running during warmup. Adjust a manual choke by shortening the cable until the choke plate closes all the way just as the knob on the dash reaches the end of its travel.
If you've got an automatic choke that's working right, it should do all the cold-start things for you- - - - -just tap the gas once and crank the engine. The choke plate should snap closed, and once the engine starts, it will release itself slightly. As long as the choke is partially applied, a "fast idle" system will keep the engine from stalling. Automatic chokes get sticky and don't close all the way, so soak the choke linkage down with lots of spray carb cleaner and work it back and forth until all the parts move freely. The choke coil should make the valve close when the engine is cold, at least enough to restrict the airflow on the first start-up. Adjust it by loosening the hold-down screws on the choke cover, and rotate it to increase the spring tension on the choke plate.
Jerry
