How do you remove fuel pump from Mitsubishi Express van?

Firstly check there is power to pump.....I think it is not uncommon to have lost power through the ECU

or the pump relay. Before you decide to drop tank, be aware that a faulty pump may not be the problem. Use small slide on connectors if testing with active(+ve) and neg (-ve) 12V...

I am not sure that the pump neg. goes directly to ground...no circuitry to hand ...both may be switched at ECU. From memory the blue wire at top of tank is the +Ve. If both are switched looking for power at the plug/socket will be ineffective because you'll likely use a lamp for that and there could be pos. but no neg. or conversely .....or neither. You'll need a multimeter volt meter/ohm-meter. One I have here of untested condition and out of the vehicle measures 3.6 ohms across the plug.

If on hoist loosen front bolts almost to end then drop the rear of the tank. You can get to it that way. If tank is damaged at rear end the pump/bracket may have been damaged. The other way...drain tank, disconnect two rubber lines and locking fuel line at front of tank. Disconnect plugs at rear including fuel gauge (side towards rear) drop tank right out. Keep all fuel lines clean and check for dirt or other obstructions in lines on tank whilst out of car...(compressed air will do)

Repair tank if required after removing pump and perhaps other gear if necessary. Don't puncture tank and do check pump is not bottoming on tank. Do a check that pump operates through socket before refitting tanl. Don't burn or damage the pins doing that! Replace tank..reconnect. Then hope for the best.