The alternator on a Ford E150 van is replaced by loosing the retaining bolts, removing the belt, disconnecting the wiring harness, and unbolting the alternator. A replacement alternator can then be put into place and reattached.
I have a 1990 e150 and it has 2.
The alternator is weak or the belt is slipping.
Check selector switch and wiring take it to the shop and find out its probably old.
1/2 inch. that's it!
It is located on the Left Side ( facing the engine) by the Alternator.
Ensure belt is on, check coolant level, check for leaks (ensure pressurized), Squeeze upper hose & check for circulation, do that when engine warming & you can tell moment when thermo. opens. Start there.
the fuse is in the dash behind the overdrive switch
Assuming the engine is running, and the charging system is in good condition. The volt drop should be almost zero. Possibilities of volt drop include. Bad earth to the component. Bad chassis earth. Bad charging system component. Bad wiring. Seized component making the alternator work harder and cutting down the voltage.
on the top of the engine compartment firewall
Check your underhood emission sticker, it will have the engine size.
Check your underhood sticker, it will have that information.