The motor should be running if it has voltage across it; use a LED indicator in parallel with it, but not 100% reliable
The motor should be running if it is drawing current; use a current-sensor in series with it, but not 100% reliable
The motor is running if its output shaft is turning; use an optical or magnetic pickup to determine that, but the pump may have failed.
The motor/pump is running if it develops pressure in the fuel line; you dont like that one. It is the only method that is 100%