1997 chevy blazer 4.3L cold hard start have to add gas to carb to start hot start is fine changed fuel filter and battery new battery it will eventually start but runs down battery.

The carby accelerator enrichment pump jet is blocked or the plunger is worn, to check this out remove the air filter look into the carby while working the accelerator , a jet of fuel should squirt evert time the accelerator is moved.

There may be a problem with the fuel pump itself or the truck may need a basic tune-up. Those would be the first two things to check. Pull a spark plug and see how it looks. If it is in really bad shape, it won't be able to fire properly and this will lead to hard starting. A set of plugs and plug wires can really wake up an older engine. The second thing to check if those are ok would be the fuel pump itself. It may be weak and take longer to build proper fuel pressure. This will have to be checked by a mechanic. The fuel pressure is very high and there are special tools that will be needed.