Drain Gas Tank

I want to remove the gas from my tank and replace it with new gas. The gas is 18 months old and I think it is causing misfire problems.

How can I drain the tank or at least remove the most of the gas. It has about 15 gallons in the tank.

It a 95 blazer 4x4 4dr 4.3.

Thanks
Bob

You cannot syphen it out,has a checkball in the fill tube.Only way I know to do it and it works,using the fuel pump.Find the fuel pump relay and remove it finding a grey wire putting a small screwdriver in that slot where the grey wire is.Hook up a jumper box with the positive cable on the small screwdriver and the negative to a good ground.Unhook at the fuel filter hooked up with a rubber hose that is made for fuel injection only.I do this with junk cars and it works

Where is the fuel pump relay and what do you mean jumper box?