I have not opened up any of the failed fuel pumps, but the main cause of a hard fail fuel pump will most likely be a worn brushes and a commutator that the insulation material between the commutator bars is keeping the brushes from making good contact to the commutator.
Exact same failure as a failed starter motor as they are both DC brush motors.
The difference is the starter can be opened up and usually the fuel pump innards are crimped inside permanently.
In addition to worn brushes and commutator you will likely find worn bushing or bearing possibly allowing the armature to drag on the inside of the field housing, partially seized bushings or bearings, leaking check valve and possibly a worn impeller and/or worn impeller housing.
Good luck finding a $5 solution to the fuel pump failures.
Last edited by jfoj; 11-02-2012 at 01:28 PM.