Too much pressure??

7psi is about the max a factory type 340 pump can put out, dead-headed.
A teener pump is usually closer to 5.5, also dead-headed..
I would think that if you have that much pressure,the float-valve is closing. I'm guessing the float is just set too high. But, IDK if the "installed" float valve can take 7psi. I know, that back in the day, they could. It could even be that the float is not properly held down with it's horseshoe-spring.