Q: When I fill my taknk up gas is on the ground under my car

Of course it is possible that a leak in a steel fuel supply line (due to corrosion), or a rubber hose, occurred after the pump was put in, but that would be quite a coincidence. More likely, if the leak started immediately after the fuel pump was replaced, the attachments to the tank, and there are quite a few, were not made properly when te fuel pump replacement was done. Some of the fittings are push on style and have internal o-rings that have to be in good condition to make a leak proof seal. Also, they must be locked securely. There are many connections to the gasoline tank and to the vehicle’s EVAP system and frankly all of them have to be "perfect" in order to avoid this sort of outcome, that is "leaks". Gasoline leaks are incredibly dangerous. If you smell vapors, those vapors can pool in low spots around your home and be set off by sparks, static electricity, and so forth and essentially amount to having a bomb around. It is strongly recommended that you request a fuel leak inspection so that the origin of the leak(s) can be identified and thence estimated for repair. In the meantime, of course do not bring the vehicle into any closed structure such as a garage, again because the fumes could accumulate in a confined space and cause an explosion.