Well for the most part fuel pumps can't usually be rebuilt. Especially if it is a newer electrical pump. You might be able to locate a rebuild kit for a old mechanical pump but it might be cheaper to buy a rebuilt one from an auto parts store.
It is very confusing and even harder to explain on here. You need to take it out of the vehicle to work on it and when you take it apart make sure you do it outside the smell of the gas will be terrible. If you are rebuilding it the directions to do so will be in the rebuild kit.
If you talking about rebuilding it, I will suggest you to take safety measures while messing with fuel pump. Make sure you do this job outside to void breathing in bad fumes. Follow all instructions on rebuild kit. Let mechanic do it if you don't know how.
It takes time to finish this kind of job. Carefully remove the old gas tank straps and replace them with new ones, when you take them off. Lower tank and unscrew giant plastic cap to lift pump out. To make things less complicated I'll say go to the auto part store to buy the cheapest rebuilt pump.
older blazer have fuel pump on the side of the motor towards the front on the drivers side, remove the fuel hoses, then the 2 bolts holding the pump in. Replace the pump with the new gasket
