Gas tank not air tight

[S13CoupeLuvr]

When installing the walbro 255 there is a rubber ring that keeps the gas tank air tight. My rubber ring is for some reason way too big to fit in the proper place. Also two of my six bolts for the fuel pump cover are missing. My question is would this cause my car to run horribly because the gas tank isn't air tight? Even when pushing the throttle to 100% the car moves so slow that a geo metro with eight people in it could pass me.Iv checked for boost leaks, changed spark plugs, ect... but i havent yet checked the injectors.

[SpeedRacer1]

Yes, a fuel tank with a leak will cause the car to bog usually under heavier throttle. If anyone wants to try this, just dont put your gas cap back on and try driving for a little while.

My ring was too big too. I just cut about a cm out of it and it worked. I would suggest you find those bolts or get new ones.