A replacement tank is 20 gallon. I had a Lincoln Town Car and it was 20 gallons so I would think that 20 gallons is probably what you have.
fuel tank capacity on 1994 Grand caravan is 77 litres.
12 Gallons (US)
My manual says fuel tank capacity is 19.0 gallons (71.9L).
According to the 1999 Mercury Grand Marquis Owner Guide : ( 71.9 liters / 19.0 U.S. gallons )
According to the 2003 Mercury Grand Marquis Owner Guide : ( 71.9 liters / 19.0 U.S. gallons )
It is underneath the car, near the left side of the fuel tank.
According to the 2003 Mercury Grand Marquis Owner Guide : The fuel tank capacity is ( 19.0 U.S. gallons )
On a 1993 Mercury Grand Marquis : The electric fuel pump is INSIDE the fuel tank
according to the website I found, a 1994 Grand Am has a fuel tank capacity of 15.2 gallons
On a 2001 Mercury Grand Marquis : The fuel tank is mounted vertically behind the rear seat
Inside the fuel tank.
( 20 U.S. gallons ) according to my Chilton's repair manual