Loud noise is not a good description. If its a loud squeal turn the air conditioner or defroster off. If the squeals goes away the compressor or the clutch for the air conditioner compressor is locked up.
The 1990 Ford Aerostar Maintenance Information manual says 21 gallons.
It might fit but it will take you a while.
The proper gap for 1990 aerostar spark plug is .044. This was taken from Dept of Motor Vehicles in Delaware. - Bill R. Jr.
You have a 21 gallon tank.
In a 1990 Ford Aerostar : You either have the 3.0 liter V6 engine or the 4.0 liter V6 engine from the factory ( each size of engine has 6 engine cylinders )
It's inside the gas tank
The distributor for a 3.0 liter in a 1990 Ford Aerostar rotates CLOCKWISE ( looking from the top ) The spark plug firing order is ( 1 - 4 - 2 - 5 - 3 - 6 ) The engine cylinder locations are numbered : 3 - 6 2 - 5 1 - 4 front of Ford Aerostar
Check the fuses first!
Under tyhe dash driver side
21 gal. probably, full it up and see.
1 - 4 - 2 - 5 - 3 - 6
A Haynes manual from Autozone and the like could have the answers you are looking for.