77 ATC 90 Not getting fuel

[MastaFlyMason]

I have a 77 ATC 90, for some reason the engine doesn't want to get gas from the carb. The 3 wheeler will fire right up if I pour some gas into the intake, but it won't run from the gas tank. The pilot jet and main jet are spotless, the carb is all very clean, the float height was just set, and the needle is not sticking. It doesn't seem like the spark plug is wet, so I'm thinking it has to be something within the carb that I just can't see. My buddy has an ATC 70, would that carb fit? I could borrow his and switch it out. Any ideas?

Not sure if this matters but the altitude changing knob thing is stuck as well and wont move

[Joseph Farrow]

Have you opened the bowl drain to see if gas is actually making it to the carb?

[coolpool]

^ Gotta do that first. And check with the petcock in the "On" and "Reserve" position. It could a clogged screen in your petcock, a clogged fuel hose or a clogged pick up tube in your tank. And also open your fuel filler cap to rule out it being clogged up.