Pull the drain plug on the bottom of the carb, catch what comes out.
If nasty, the tank will need to come off and be rinsed out with E85.
Check the flow, should have a healthy stream, not a drip or stop completely. If not a good flow, check for restrictions back to the tank. There should also be a screen in the carb inlet elbow. If there is an inline filter, that can be the problem. They don't do well with gravity flow systems.
The carb may also be contaminated inside. Usually it can be removed, eased apart and cleaned without a kit, just be careful with the gasket. It is easier to disconnect the link from the governor arm than trying to work behind the carb.