I had a 93 F150,302 and the fan clutch to water pump was held on by (4) nuts and lock washers via studs in the water pump pulley. Even if yours is an I6 i'm sure its similar. The hole of the fan clutch that connects to the water pump pulley shaft might be rusted on there. Spray some PB Blaster in there and let it sit for awhile. Other then that,I have no idea!