2001 GMC Sierra Poor fuel mileage

2001 GMC SIERRA
59,000 MILES • V8 • 4WD • AUTOMATIC
Avatar
WATERGUYSID
  • MEMBER
  • 1 POST
I have a 1500HD w/ 6.0L. What would cause my mileage to drop to 8.5-9 mpg from 10.5-11? I changed the plugs, and went to synthetic oil, nothing seems to help.
Aug 6, 2008 at 5:29 PM
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.
Advertisement
Avatar
BLACKOP555
  • CAR REPAIR CONTRIBUTOR
  • 10,386 POSTS
you can change the air filter, and check to see if the tires are inflated properly, also make sure the brakes arent dragging.

i woudl suspect a issue with the o2 sensor, due to its not that much of a decrease.
Aug 6, 2008 at 10:12 PM
Advertisement