[QUOTE=Mrgdc34;411297]

I was filling up this hummer I just picked up a few days ago and I just noticed all this fuel coming out from the bottom how can I stop it?

 

If you take enough pictures of the leak and its puddle, the cyber digital film with stop the leak. Or not.....

How about you get under and LOOK where the leak is coming from and then repair it. Is it a gas line, or a hole in the tank?

 

is it leaking when running or when fueling or maybe parked
might be a rotted pump or pump line fitting when running. if that is the case then also check your brake lines as they probably are also rotted.
if when fueling maybe the filler tube is loose or bad

 

I noticed in the one picture is gas cap is off, so I assume the photo was taken out the gas station?

Not sure of the model year. If it's a 2003 it could be the fuel filter right in front of the fuel tank above the crossmember. If it was never changed, rusted out. Then there's the vapor canister and such right there on the driver side in front of the tank, outside of the frame rail. Then forward of the fuel tank you have either one or two quick release fittings in the fuel lines, depending on the model year. Fuel lines are plastic.

Check the forum. Read something recently about fuel being diverted to the vapor canister when filling.

 

This YT video may help with your investigation.