how can i fix an electric fuel pump with 5 pins to a fuel tank that has a 4 pin socket connector?

Question

I BOUGHT AN ELECTRIC FUEL PUMP FOR MY MBI40 BUS ..THE PUMP HAS A 5 PIN PLUG AND THE SOCKET IN THE FUEL TANK IS A 4 PIN SOCKET

Answer 1

apparently - you got the wrong part for the right tank -

which means

you got a 'special model' where a substitution was made

may need to dig deeper - see if you can take the part back -
Auto Zone, NAPA, or Advance should know about the problem

last resort - take it to the dealer = they had BETTER know!

best of luck!