MANDALAY
Like i said DISCONNECT that plug. Put the factory recommended fuse in 15 amps then turn on the ignition. Does the fuse blow ? 

He has already done this :

nissky
Connected everything else back to normal except fuel pump connector. 
It runs.

The pump was running on a jury rigged supply but everything else powered by that circuit was connected as normal - no fuse blew.
 
The symptoms and diagnosis thus far point to an excessive current draw issue by SOMETHING on that circuit.  It COULD be the fuel pump failing and this is most likely, but you'd want to be absolutely certain before dropping the tank.  If your multimeter has a 20A range (or higher), you can use your jury rigged fuel pump power circuit to measure the pump current, just connect the multimeter set to its 20A range IN SERIES with the pump, and it will directly measure the pump current.  I'd estimate it should draw no more than around 8A, but see if you can find a more definite spec to compare to.
 
  Edit: Just to clarify, something on the 15A EFI fuse circuit is drawing more current than it should, such that with everything connected the TOTAL current draw is too much for the 15A fuse.  You'd probably find that disconnecting the O2 sensor heater would also prevent the fuse blowing, as it removes the "straw" that's breaking the 15A "camel's back."
 
This is what makes it more difficult to diagnose, a dead short can be found easily, but excess current draw is a more subtle effect that as you've discovered can be masked by fitting a higher rated fuse.  As Mandalay said, not a good idea!