Is there a specific way to install the fuel pump into an s5? My fuel pump seems to be a bit faulty; previous owner said he installed a walbro. Sometimes it reads the gauge, but while driving on freeway or around town the gauge likes to drop randomly, but comes back up sometimes. I filled half tank yesterday and it finally reads it, but started doing this problem again. Before for awhile, it stopped working and always stayed below E even though there's a lot of gas in the tank.

I also replaced my fuel pump with a stock one from my other s5 and still did the same thing. Not sure if it's the fuel pump or wiring or I'm putting the pump in wrong. In the gas tank, I see there's a circle within the tank. Am I supposed to put the floater on the outside of the thin wall of the circle or within with the fuel pump?

 

The float goes all the way inside right next to the fuel pump