Art20c

87 s4, auto, pases NY state inspection with almost 0 in readings. City mileage 5.9 miles per gallon of normal driving, on highway 20.89. Why such a big difference, and city mileage doesn't look good. What could be a problem?

AO

WOT switch could be stuck? Do you do a lot of idling? HWY mileage sounds about right. How does the car drive in the city? DO you have a 16YO son who needs gas?

Mrmerlin

sounds like you might have a bad calculator because the city numbers dont come anywhere near the highway numbers.
OR someone is siphoning off your fuel, OR you have a fuel leak OR your not filling the tank all the way, but taking for granted it isOr the over flow/equaliser line is plugged so not letting you fill the tank although this wouldnt explain the highway milage

blown 87

If it is actually burning that much fuel, two things are going to happen, black smoke and the rings are going to get washed down.

bigmac

Could city be 15.9?, That would be about right. Did you just install a RMB?

Art20c

Guys, WOT is OK, because car passes NY state inspection like that, with almost little over 0 on all readings, I dont have any kids living with me who might need gas.

Now about numbers:

Last week I put $20 worth of gasoline at 3.73 per gallon(5.36 gal) as soon as light came on. Reset odometer to 0. Drove from home to work and back, which is about 6 miles both ways, regular city driving, couple of traffic lights, couple of turns. Gas light went on again at 32 miles on odometer(5.97 miles per gallon).

Didn't touch the car 'til this morning, I knew that I had to go to Hamptons, which is primarily is a highway drive. Put $30 at 3.73(8.04 gal), set odometer to 0, drove 168 miles until gas light came on again, what makes 20.89 MPG.

City mileage was like that for quite a while, but I never compared it to hgwy mileage, like I did today, and I don't like these figures.

I did smell gasoline at rear outside of the car, but not inside, no more then just couple of times. Looked under car, didn't see anything. Beside that, car runs perfect, steady idle, good acceleration, no smoke or smell of rich burning.
Is there any way to check if gasoline is leaking from lines except visual inspection?

P.S. Spark plugs are clean, color of a central electrode is light beige.

ew928

Possible to test other end of the gas gauge/system.

Fill up tank. (I know. Bring the Platinum card)
Run X number of city/mix miles.
Then fill up tank again.

IcemanG17

Your hwy mileage is right...your in town mileage is HORRIBLE.....my 88 auto has the same gearing as you......when I go to a DE (drivers education track day) I fill up at the station...drive about 5 miles to the track then drive the track all day & back to the station before heading home....I typically get 7-8mpg when driving at track pace or lots of full throttle redline shifts, 1-2 hours of track time & I would guess 20% or more at full throttle near redline....thats like 48 minutes at redline!!!!!!!!!!!!!!!!!!! based on a 2 hour track day....

Typically when my gas light comes on it takes between 18.5-19 gallons to fill up..... I would try this...fill the tank all the way up....drive normally for the full tank, wherever you go.... See where the average falls then..... You should get at least 12mpg in town unless your really footing it

Art20c

Will do that, way I drive is very conservative, no flooring and then braking, Im not trying to prove anything while driving.

AO

I think the method you used is flawed - the light may not be super accurate. Follow EW's advice. Fill it up and set odometer to 0. Drive X miles (city or Hwy) and then refill. Record the # of gallons taken. Divide # of miles by # of gallons. Record fuel economy. Lather, rinse, repeat.