Here is the steps in required in repairing a broken cast iron base to a gas pump. This particular base is off of a Wayne 866 but the process is the same for most all pumps.
This first picture shows the "two piece" base


Here the edges are ground down to a taper to allow good weld penetration


Next, the base is heated to prevent cracking from the weld



This is the welding rod (nickel) used to weld the casting