onetongmc: You should not have to add fuel to start. Possible troubles can be many.
Do you have fuel delivery to the floatbowl? Are gas lines and/or fuel filter blocked? The idle mixture may not be set correctly, and possible vacuum leak, and/or plugged idle port, or the engine would/should start. Accelerator pump may be worn/leaking and not performing to specs. Float needle/seat may be worn or float level not set correctly. The list goes on!
When you buy a used carb you don't know what kind of shape its in, or how long its been sitting, your setting yourself up for trouble ahead!! Sometimes there plugged up and/or gummy and dirty. Usually full of trash. Even if you have picked up a brand new carb, you still have to check things out and adjust as needed. Just because something may be new, does not guarantee its right and/or adjusted correctly.
You are at a point where you have to make a decision about your next move. You have 2 choices. 1. You have to pay a shop to fix your carb. 2. Or educate yourself about your carb/truck and fix it yourself.
If I were you, I would go with number 2 because its cheaper and more fun. Carb repair is not hard, deep, or involved. Arm yourself with some knowledge. Buy a shop manual for your truck, or book on your engine/carb. In it, will be a section on your carb, and will take you through a step-by-step explaination of all the carbs systems, and overhaul, and any and all necessary adjustments.
You can buy a carb rebuild kit from the nearest NAPA or autoparts store. Most carb kits include instructions, complete enough to guide you through what you need to do and adjust. No rocket science here, just basic "Stovebolt Science 101". Piece of cake!!!
Hope this helps!!!
