Remove the supply hose to the carb, and shove it in a beaker of water and turn the engine over, the bubbles of gas coming out of the hose will give you some idea of what is being supplied, examine the inletto the carb I had one that was practiclly blocked with heavy ends so make sure inlet is clear. If your happy plenty of gas is being supplied screw up the air screw on thside of the carb untill the truck starts from cold, to-much air may be weakening the gas air ratio.

Regards Titus