return pump and over flow

i just took the overflow box out lol seems fine to mee i put a screen over the pvc pipe whats going wrong sump emptys to fast or the sump fills to quickly

 

You need a standpipe that maintains a preset level in the overflow or display and draws air in as it drains so it flows at maximum capacity. Without an air intake a standpipe will not flow properly and can air bind or back up or burp causing floods and flushing action.

Look at the Herbie method, Stockman, Durso and many others that have worked well for years. The key is getting the right balanced air/water mixture and it flows like crazy with little noise.