2002 GMC Sonoma Poor Fuel Mileage

2002 GMC SONOMA
73,000 MILES • 6 CYL • 4WD • AUTOMATIC
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NITREX
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I bought this truck 4 months ago and the fuel mileage has gotten worse. The previous owner, who is a good friend got 19-20mpg. I am only getting 14-15mpg. It seems to be poor whether I drive in the city or on long trips. Tire pressure is good, air filter is new. regular oil changes (3000miles) with Mobil 1 synthetic it's whole life. I tried a fuel system cleaner in the last tank of fuel with no change in mileage. Any ideas on where to start?

Thanks
Mar 11, 2010 at 1:46 PM
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HMAC300
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  • 48,601 POSTS
different drivers get different fuel mileage due to the way they drive their vehicles. Do you do fast starts, stop your vehicle with the left foot? these are a few of the things. But get your engine scanned tosee if there are any codes. then have them check the vehicle ofr a blocked/plugged catalytic converter. If you have low vacuum on the engine that may be one thing causing it. the 19-20 range on those vehicles is mostly eway drinving not city. if the truck has different size tires that can effect it as well.
Apr 3, 2010 at 10:41 AM