Ahh, bad fuel pump

Engine idling in closed loop at operating temp, trans in park or neutral, all accessories off, RPM should be 650.

 

I'm having trouble pumping gas I get 3/4 of a gallon and it clicks off like it's full but it's not

 

There is a restriction in the fuel fill tube. Could be the anti-siphon valve in the lower end of the steel filler neck is jammed. Plastic ball, about like a ping pong ball, inside the filler neck to prevent siphoning fuel. Right where the steel filler neck changes to rubber, give it a whack.