Let's get this gas mileage thing down!

Discussion in '80-Series Tech' started by livelarg, Jun 30, 2005.

  1. livelarg

    livelarg

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    All right, I have a 92 cruiser' with 210K miles.
    I have read about peoples different cruisers, and i have heard that some people are getting 13-16 mpg, while others, including myself are getting under 10 mpg.
    So this in my question. I know I have many miles, but what do you think the reason for such different mileage between trucks?
    What are some ideas that would cause for a dramatic loss in mileage. I have done a full tune up, I do have some 32x12.5 off-road tires, but I am getting 7-9 mpg.
    What are ideas to make it better?
    All right, lets hear it

    Kent :confused:
     
  2. stuck in GA

    stuck in GA

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    Get a Honda. :flipoff2: No but seriously I have never heard of getting 7 miles to the gallon with 32 inch tires. Are you sure you aren't putting some homebrewed stuff into your tank?
     
  3. livelarg

    livelarg

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    I wish that was all it was.
    Hell, my truck will get just about anywhere, as long as there is a gas station near it.
     
  4. Fly Rod

    Fly Rod

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    Shoot, I wouldn't know! My stock 95 got 16.85 mpg over 700 hwy miles. Around town is running @ 14mpg.

    Try a clean air filter, new plugs and wires and synthetics all around. Some engines respond to different oils with increased mpg. How old is your cat?

    Just throwing darts.

    Fly Rod
     
  5. IdahoDoug

    IdahoDoug

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    Did you correct the MPG for the larger miles??

    DougM
     
  6. Silicon 70

    Silicon 70

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    How about cleaning your fuel system. Try the pure techron stuff that'll treat 20 gallons, it's like $10 at the auto parts store. Oh and treat it twice this is the key.

    I have a 92 FJ that runs smoother and gets 4-5 more MPG after doing the fuel treatment, but then again I'm running stock tires.
     
  7. livelarg

    livelarg

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    I ran the seafoam through the gas and the whole pvc valve thing, not much better.
    The cats are prolly the originals, the only other thing that I didn't do is the o2 sensor. That is next on the list (they are pretty pricey).

    thanks for the ideas,keep em' coming

    kent
     
  8. whodat

    whodat

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    livelarge, Doug made a good observation. Your calculations could be incorrect because your speedo thinks you're going slower than you actually are.

     
  9. Boston Mangler

    Boston Mangler

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    I had a 91 with around 95k that was all tuned up, synthetics and stock tires and i averaged 9-11mpg.

    I now have a 93 and will be seeing how that does as well soon.

    Proper tire inflation also helps out more then you might think!
     
  10. whodat

    whodat

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    in other words...the odomoeter measures less miles when you have bigger tires.

     
  11. MaddMatt

    MaddMatt

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    I think you've got an issue somewhere. I have an '89 3FE with 230k, a spotty previous owner history and running BFG 32X11.50's, and I routinely get 14+ uncorrected, about 16 corrected. I determined at one point that my tires are about 13% larger than stock.

    I drove a round trip of nearly 500 miles on tuesday, including two passes near or over 11,000 feet, and still got 14.5 (16.38)

    I don't know where to tell you to look, but something is definitely holding you back. Since you just had a tune up, we'll assume your filters are clean and plugs are new? I believe in '92 you're still running the 3FE, correct? I would suggest going through the miles of vacuum hoses and looking for a bad one. Every time my engine starts missing or running roughly, I've been able to trace it to a bad vacuum hose. Good luck.
    -Matt
     
  12. Romer

    Romer fatherofdaughterofromer Moderator

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    I believe Doug means larger tires :D

    My 285's are about 6% over stock in size, so when I figure gas mileage, I take whats on the odmeter and multiply by 1.06 for the mileage to use in the calculation. That would not explain your difference though
     
  13. snowwolfwarrior

    snowwolfwarrior

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    mine here in the UK done 560 miles on two full tanks of fuel, work that one out?
     
  14. chiz45

    chiz45

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    96 cruiser, 119k, no speedo correction, stock gearing, 285/75/16, 225 miles on the trip meter = 20 gal fill up (and $50 poorer). Using Romer's figure, it should read 240 miles. That works out to about 12 MPG mixed city/hwy. I have never taken it on a trip far enough to measure solely hwy miles.

    Would different octane gas have a noticeable effect?
     
  15. cruiserman

    cruiserman

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    Right, but fj62s came with 28s, and the 80s came with 31s. BFGs run small, so IMO his correction would be minimal. Use a GPS to figure it out.
     
  16. White Shark

    White Shark

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    My stock 92 was pulling 14-15 mpg with the original size/style tires and 110K miles. Around 200K miles, OME lift, ARB bumpers, 33" M/T tires, etc. it was getting 10-11 mpg. With the Chevy 350 and a Kaymar roofrack and tire on the top, I'm getting 11-12 mpg. Without the rack and tire on top, I figure I'd get 14 or so.
     
  17. gorister

    gorister

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    My 91 with 31x10.50's consistently sees 9-10mpg for normal daily driving (10% interstate) and about 14mpg over 200 miles of interstate driving. 170k miles. Does that sound about consistant?
     
  18. snowwolfwarrior

    snowwolfwarrior

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    so on a full tank, standard car, what is the usual miles you would get from full to orange light? I get 280 miles
     
  19. Jim_Chow

    Jim_Chow

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    Even if you're using the correct gears for the tire size, most likely, the speedo is off. Best way to test it is to calibrate your speedo vs. the interstate highway mile markers over a reasonably long distance (say 10 miles or a multiple of ten...the more miles, the less error). You can then determine how your speedo is reading. I found my odometer/speedometer reads 2.5-3% higher than actual, so I have to subtract that off my calculated mpg.
     
  20. TomH

    TomH SILVER Star

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    I grabbed this from another thread.


     
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