1992 Mitsubishi Mighty Max Too much fuel

I bought a 1992 mighty max that has been sitting for 4 years the guy I bought it from said the head needed 5 be rebuilt and there was a extra motor in the back and the original head in the back we took the head off the motor cleaned up the original and put it on. Runs has a miss. The fuel pump us always on when you hook the battery up. When it's started and you unplug the fuel pump it clears up and sounds like it's supposed to I switched the regulator and fuel rail and it's still doing the same thing. The pump is just giving the engine too much gas to be normal