Why does the fuel pump fuse keep blowing on a 2003 mustang gt? on 2003 Ford Mustang GT

I have changed the fuel pump, the relay and the constant relay. Paid a mechanic to fix it but he could not.

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1 answer 1 comment
TO MUCH RESISTANCE IN CIRCUIT. CK FOR CORRISION ON PLUGS AND WIRING AND ANY OTHER CONNECTION
It's not that; I've checked all wiring and plugs. Any other ideas?