According to my Chilton's Auto Repair Manual :
The ( 1987 ) Mercury Grand Marquis holds ( 20 U.S. gallons )
according to the owners manual for my 1987 Grand Wagoneer, it holds 20.3 gallons
shock absorbers
how to remove right turn signal relay on 1986 mercury grand marquis
The most common order is 13726548.
Behind the intake plenum.
orange button in the glove compartment.
The Mercury Grand Marquis is a nice big car, especially those from 1986, very roomy for those who are tall, with long legs. The original tires size for this vehicle is 215/70-15. There is no other size suggestions for this vehicle.
Mercury outboards of 1986 lineage require a 50:1 ratio. One pint of 2 cycle oil, to six gallons of fuel.
the fuel capacity for jeep grand wagoneer in the 80s is between 22 gallons and 25 gallons depending on the engine size
firewall 4 - 8 3 - 7 2 - 6 1 - 5 front of Mercury Grand Marquis
Wheels from a concurrent Mercury Grand Marquis or a Lincoln Town Car would fit.
I'm not sure if the 1986 is the same as the 1987 , but ( on the 1987 Mercury Grand Marquis the 5.0 liter / 302 cubic inch V8 engine is rated at 150 horsepower and the 5.8 liter / 351 cubic inch V8 engine is rated at 180 horsepower according to my Chilton's Auto Repair Manual )