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mjmason13
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Feb 10, 2010, 6:52 AM
Post #1 of 7
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Improve gas mileage?
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I have a 1986 Chevy G-20 conversion van 5.0 with 78,000 miles. Runs great, just tuned it up, new air filter, oil change, but only gets 8 miles per gallon, mostly highway? Any suggestions.
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prolube
User
Feb 10, 2010, 10:26 AM
Post #2 of 7
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Re: Improve gas mileage?
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is it fuel injected if so try cleaning the injectors. also run a can of seafoam into the intake thru a vacuum port to help clean the carbon off the intake but be carefull not to put to much in to fast. u mentioned u did a tune-up did u change the fuel filter?
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nickwarner
Veteran
/ Moderator
Feb 10, 2010, 11:28 AM
Post #3 of 7
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Re: Improve gas mileage?
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have you checked the chassis for any possible cause there? With the age and low miles it must've sat a good bit. Have you checked any of the brakes to ensure they aren't dragging a bit? It might not be noticable when you drive it if it's light drag but it will definately pull your mileage down a bit.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Feb 10, 2010, 2:35 PM
Post #4 of 7
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Re: Improve gas mileage?
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mj: A whole slew of things are involved with MPGs. One check isn't enough. Allow two or more known good fill ups and do the math.
The biggies are tires + tire pressure and the way you drive. Wind resistance is exponential meaning doubled speed = three times the resistance. That the effect that allows mega ton aircraft to fly!
T
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re-tired
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/ Moderator
Feb 10, 2010, 4:56 PM
Post #5 of 7
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What type of conversion did you get ? A high topper (raised roof) plush carpet with extra sound proofing plus captain seats , a sink ,paneling and storage bins add hundreds of pounds plus increases wind resistance . A slew of electronics (TV,VCR,STEREO,CUSTOM LIGHTING,ETC) not only adds weight but also increases electrical load on alternator which makes the eng work harder . My in laws + me ,wife and son drove from Miami to Los Angeles in a new 87 chevy conversion van . We averaged 8 -12 mpg depending on driver and terrain .
LIFE'S SHORT GO FISH
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valpoautodummy
New User
Feb 10, 2010, 9:35 PM
Post #6 of 7
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Re: Improve gas mileage?
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 drive slow. if u drive less than 55mph you will save a ton of $ on gas 
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re-tired
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/ Moderator
Feb 10, 2010, 10:38 PM
Post #7 of 7
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Re: Improve gas mileage?
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Drive less thsn 55 on the interstate and and not only will you endanger you and your passengers you become a hazard . Most modern cars are have computer programed for and geared for posted highway speeds . For example on a recent 1200 mile trip using my cars onboard mileage computer I averaged 2.5 mpg better at 70 than at 55-60.
LIFE'S SHORT GO FISH
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