According to my Chilton's Auto Repair Manual :
A ( 1991 ) Mercury Cougar has a ( 19.0 US. gallon gas tank )
The fuel tank capacity is 18 gallons
According to the 1999 Mercury Cougar Owner Guide : ( 58.5 litres / 15.4 U.S. gallons )
It should be 15.5 gallons
The fuel tank capacity should be 58.5 liters or 15.4 gallons
On a 1999 Mercury Cougar : The ELECTRIC fuel pump is INSIDE the fuel tank It is installed through an access hole in the top of the fuel tank
Look either in the kick panels or the driver's side trunk panel
21 U.S. gallons ( 18.8 gallons , supercharged version ) according to my Chilton book
In the fuel tank
Yes
its in the fuel tank repair about 700.00
Inside the fuel tank
The primary cause for jerking on a 99 Mercury Cougar is the engine not getting enough fuel. This can be a sign of a clogged fuel filter, bad fuel pump, or clogged fuel injectors.