Trips ground fault on plugging into receptacle

coffee maker works when not using plug with ground fault protection but on any receptacle with ground fault protection the ground fault is tripped on plugging into receptacle. this does not require cutting the unit on. this has happened on receptacles on differnet ground faults so it does not appear to be the ground fault. i was told it was probably the heating element but why would this trip the ground fault before cutting the unit on. any suggestions? thanks for your help.