weird gas mileage problem!?

[jasonsos]

Greetings Infiniti Die-hards!The two topics I have posted since I joined only a few weeks ago helped to to solve those problems, thanks to all of those who replied.Now, I have a 'weird' gas/mileage problem that I must seek your help/advice on: I have a 1993 J30t, which the Owner's Manual states has a 19 gallon gas tank. Out of habit from my former Jeep that had a broken gas gauge; I zero the odometer each time I fill up. I still do this with my Infiniti. It seems that half full (or, half empty), is when I get gasoline, which is between 9.5 to 10 gallons. The odometer reads about 109 miles at this point. That equals about 10 miles per gallon! Something HAS to be wrong, as my Jeep had a larger engine (a in-line 4.0 liter, compared to a 3.0 liter Infiniti V-6). The Jeep had a 14.5 gallon tank, so I would get about 270 miles per tank with it, and it was a 5 speed manual trany.I don't think that I have a gas leak, as I don't smell gas with the exception of when it first starts up, and my Infinity starts right up--real quickly.Any ideas? It passed the high Texas Inspection in which they test the ozone stuff that also checks the richness of the gas flow.Could I be having a gas leak while driving and just not know of it, although, once again, I ride with cracks in the windows cos I smoke, or I have the sunroof open: no gasoline orders!Please give me some direction if you would.Thanks to all who reply!!!Jasonsos

[bullittandy]

Are you pumping 10 gallons of gas into the car after driving 109 miles or are you estimating using the gas gauge?If its the latter then the gas gauge is not that accurate, if its the former then you need a serious tune up or have another major malfunction.Good luck!

[elwesso]

Is this on HIGHWAY driving or IN TOWN CITY driving (say less than 15 miles per startup)?

makes a BIG difference. Not sure if Texas has crappy gas or not.

[maxnix]

Dallas and Houston now have ethanol in the winter blend.

[purplesignal]

I have a 93J, and i live in the Dallas area. I get about 145 ~ 162 miles when my gas gauge hits half full/empty. I average between 20~22 mpg based on 50% highway and 50% local driving. I believe others on this forum are able to get 24 ~ 26 mpg for the J30s. Things I would check:- spark plugs- MAF sensor- throttle body- air filter- O2 sensor

I also noticed that I get the best mpg when I use 93 Texaco with Techron. I tried 93 Shell V-power for awhile, but was getting mpg's in the high 19's.