I have a 91 240SX and had a similar issue, my Fuel Pump had to be replaced.
The fuel pump is shorting out and that is why the ecm fuse is blowing .Disconnect the the fuel pump and try it again,if the fuse blow's again then it is not the fuel pump.
the fuel pump tank wiring is faulty at the pump
Short in the wiring or a bad fuel pump.
An electrical short between the fuse and your fuel pump, I would replace the fuel pump first..
Disconnect the harness at the fuel pump and replace the fuse. If your fuse doesn't blow after turning the ignition on, you probably have a bad fuel pump, check it for shorts.
You may have a problem in the pump. Take it off and check .
Fuel pump
most likely a faulty fuel pump.
Short in wiring, relay or pump? internal problem in fuel pump.
There is a short in the wiring or the fuel pump has locked up.There is a short in the wiring or the fuel pump has locked up.
Failed fuel pump, or a short to ground in the wiring to the pump.
Failed pump, or wiring shorted to ground.