There is only one filter, it is under the car, passenger side, near the back. It is held on by plastic clips that are EASY to break. The sock in the fuel tank is not intended to be serviced on any regular basis, don't worry about it.
AnswerTechnically, there are two fuel filters on your '99 Marq. Only one is readily changeable though. You can easily change the fuel filter, but the fuel sock is another story.The fuel filter is against the inside of the frame rail (driver's side in front of the rear wheel on early 90's models, passenger's side in front of the rear wheel on later 90's onward models), and the fuel sock is attached to the inlet of the fuel pump and is inside the gas tank.
As someone who just had to replace the fuel pump on his '92 Marq, I am telling you that you don't want to try changing the fuel sock on a whim.
ONE - located in the Gas Tank
According to the 1999 Mercury Grand Marquis Owner Guide : ( 71.9 liters / 19.0 U.S. gallons )
It only has one.
According to the 1999 Mercury Grand Marquis Owner Guide : It is NOT a flex fuel engine ( use " regular " unleaded gasoline , 87 octane )
On a 1993 Mercury Grand Marquis : The electric fuel pump is INSIDE the fuel tank
One above the tank, and a screen on the bottom of the pump.
On a 2001 Mercury Grand Marquis : The fuel tank is mounted vertically behind the rear seat
Inside the fuel tank.
Yes , the 4.6 liter , SOHC , V8 engine in a 1992 Mercury Grand Marquis is fuel injected
Call for help. Fuel pump is INSIDE the fuel tank. The entire tank needs to be removed to get at the electric pump.
19 U.S. gallons ( 71.9 liters ) according to the owners manual
Only one - it's inside the gas tank. --------------------------------------------------------------------------------------------- The fuel filter is underneath the 2008 Mercury Grand Marquis ( I believe under the passenger side of the vehicle ) mounted on the frame . The ELECTRIC fuel pump INSIDE the gas tank has a " sock " on the end of the pickup end Helpfull ( the first answer is not mine , the corrected answer is )