Welcome to JUST ANSWER small engines, let me try to help you !!
You have looked into the tank, and nothing floating in the tank that might get against the suction tube when going up a hill?
Have you removed the suction tube from the tank and checked it for holes or debris? Last have you adjusted the float level to let more fuel into the float bowl??
I'm thinking you have something in the fuel tank!
Try a test line from the fuel pump inlet into a separate fuel container and run the hill!
R u refering to the float level in the carb?
Yes on the float level. Have you checked the tank and the suction tube?
I used a sucksion tube to suck out anfy visible debris in the tank. even snipped iff a 1/4 in of the tube so it would not fall back against the slanted portion of the bottom of he tank and get stuck against the bottom.
Have you tried it in a separate fuel container, that would eliminate the tank and the fuel lines. Just attach it to the in side of the fuel pump.
I'll try that in a couple of days and let ya know. the golf cart is at the lake....several miles from me but I'll let ya know