It's a big deal, 'cause it's INSIDE the gas tank. Haffta drop the whole gas tank to get at it.
According to the 1999 Mercury Grand Marquis Owner Guide : ( 71.9 liters / 19.0 U.S. gallons )
You do not need to remove the fuel rail to remove the spark plugs.
You must drop the fuel tank to access the pump.
do you have to remove fuel tank to replace fuel pump
You can buy a siphon kit at your local auto parts.
Fuel pump is located in the trunk on the left side you have to remove the interior panel
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
On a 1985 Mercury Grand Marquis, the fuel pump is located inside the fuel tank. To access it, you'll typically need to remove the tank from the vehicle, as it is not externally accessible. It's advisable to disconnect the battery and relieve fuel system pressure before attempting to remove the tank for safety.
On a 2001 Mercury Grand Marquis : The fuel tank is mounted vertically behind the rear seat
Inside the fuel tank.
You have to remove the gas tank because the filter is inside the. This is NOT an easy job. I recommend you pay someone to do it right. Cost around $400.