2000 Mercury Marquis V8 Two Wheel Drive Automatic 145000 miles
(2000 mercury grand marquis) fuel filter, spark plugs, upstream o2 sensors, new mass air flow sensor, air filter, at fluid and filter change, inflate tire to 38 psi, change diffrential oil. Scanned pcm twice and checked for vacum leaks and catalytic converter blockage all fine. There is no brake drag symptoms or backpressure caused by bad cats, all checked fine but my problem is that my gas mileage is horrible I get 180 miles in city and 200 miles highway and 220-230 miles if on a long highway going at 60-75 miles with light foot in either situations and I am sure that the odometer is fine and accurate because most of my driving is highway and I always reset the trip meter when I fill up the tank. The fuel sending unit is okay because it takes 13-14 gallons to fill up I have scanned the vehicle a third time yesterday and made the technicians inspect the vehicle and they could not find any thing. They told me that the fuel vapor canister could be the problem but they are not sure. Besides I could not find any thing on the internet that confirm this or that it has any thing to do with gas mileage and by the way my gas mileage have not changed not even 1mpg. Please help me It is driving me crazy all I can think of now is the fuel vapor canister and the fuel pressure regulator and the fuel injectors though my car accelerate just fine and has no problems or misfire or any thing that indicates problems and by the way my brother has a 99 crown vic and gets 300 miles till the low fuel light comes on and I gave him my my car to test it and he said that it does accelerates fine just like his car and he felt that my car had better horse power at hard accleration but that is because my car is a dual exhaust with 215 hp and his is single exhaust with 200hp. Thanks
tHE CAR RUNS LIKE A BUTTERFLY AND SMOOTH AS SILK AND CONSUME A VERY LITTLE OIL CONSIDERING ITS AGE
THE ALIGNMENT IS OKAY
PLEASE HELP ME AND TELL ME WHERE TO START
I SEARCHED EVERY THREAD ON EVERY CROWN VIC, GRAND MARQUIS, TOWN CAR AND COMPARING THE GAS MILEAGE THE WORST PEOPLE GOT LIKE 280 AND THET WERE COMPLAINING.I HAVE BEEN MONITORING MY ELECTRONIC FUEL GAUGE AND IT IS WORKING AND READING ACCURATELY.
I HAVE BEEN DOING MY BEST TO SOLVE THIS MYSTERY WITH NO LUCK