What kind of mpg is everyone getting from there Grand Marquis? I have an 85 with a carbed 302 that got 11 mpg last time i filled up, i just filled up yesterday morning, only traveled about 18 miles and its showing i already used a quarter of a tank of gas. is that normal? ive adjusted the carb so it wont run rich like it had been plus i replaced the spark plugs. the car has over 150k on it. but back to my question what kind of mpg is everyone getting?

 

I have the 88 MGM with the speed density EFI system and originally got 11.5 around town and 18 on the highway when I got it. I'm getting 14 around town now and almost 22 on the highway (but I added dual exhaust, fresh air ram intake behind the grill, wide range gear-set to the AOD, along with the top end tune-up: wires, rotor, cap, plugs).

The 302 was never a good gas mileage engine. It was a good power engine though. There are ways to make it good, but they involve better cam, firing order change to match the cam, better heads, and pistons made for the more aggressive valve timing. Get a good high flow intake (like from an HO or an aftermarket intake) and then you can start getting better gas mileage.

as for the gas gauge, the float may need replacing in yours. Mine generally shows a quarter tank gone at bout 50 miles. but if you're in cold weather that makes the car take a while to warm up, it may drain a quarter tank by 25 miles. The old 302s really like to drink when cold.

 

ive considered doin some changes, but since im just driving this thing till i can afford a better car. i just dont think its worth it unless i was goin to keep the motor. this is really a throw away car for me.

 

I think my 89 was carbed. 28 mpg highway, 23 combined high/city.
My 97 was getting 23 high/city, same trip now is 19 winter????
Wifes 08 mexican lincoln v6 gets 24 highway, 16 city, although after 1000 miles 1 hole shot drops the computer readout to 19. But it does get up and GO at wfo. Funny how those numbers don't agree with the door sticker at the dealer. "your actual mileage may vary" My older cars all surpassed the stickers

 

my grandpa used to have a 87 colony park wagon, and claimed it got around 20 mpg with it. he ended up trading it in along with a 98 protege on a 07 kia optima that gets only about 25 mpg.

 

'93 Grand Marquis 4.6L w/ newly rebuilt AODE

87 Octane:
City- 19
Highway- 23

87 Octane and 2oz/10gal Acetone:
City- 21
Highway- 28

Don't really want to make this thread into an argument for or against using acetone in your gas, but short story goes that acetone breaks gasoline's surface tension allowing a better fuel/air mixture and a better combustion. That all results in better fuel mileage.

I was looking into the Ford Flex, but I couldn't believe I'm getting better gas mileage with this boat! I'm not a lightfoot either.

 

My '91 Crown Vic completely stock got about 10-12 around town and at best 14 on the highway.. After "fixing" the catalytic converters it jumped to about 14-16 around town and and low to mid 20's on the highway... Where I would buy gas made some noticable differences on this..

 

'93 vic - completely stock with near 200K miles - 19 city, 27 hwy. usually average around 22 with the current mix of driving.

running 89 octane generally due to 87 + ethanol (current pump gas) giving the car lots of chatter. Used to be able to run 87 octane in it with no trouble before ethanol was introduced to pump gas.

 

ok this is off topic, but today goin to and from work i almost staled my car 4 times. 2 times i was slowing down to almost a complete stop, once i had come to a complete stop on a hill and then when i was turning from one road to another. not sure why it wanted to quit like that. i had no problems when i went to lunch. any ideas why it did that? carb problems?

 

sounds like carb trouble. might need to tweak the idle and fast idle. sounds like the fast idle (warm-up idle) may be too low. The choke may also not be working right.