Backfire under loading going up hills in second and third gears?

1993 TOYOTA PICKUP
305,000 MILES • 3.0L • V6 • 4WD • MANUAL
Avatar
TOYOTA200010
  • MEMBER
  • 1 POST
My truck recently started back firing and rear end vibration/ hopping while going uphill at a steep grade. Only time it happens is put hill. Not on start nor flats or downhill. After warming up it idles around 500 RPMs when its set at 700. After driving for 5-10 minutes idle sits at 700 RPMs. Also smell of gas/oil on startup through heat/AC vents into the cab then goes away after 2-5 minutes.
Aug 1, 2023 at 5:12 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
STRAILER
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 54,180 POSTS
A backfire can be a misfire or lean fuel mixture. I would do a full tune up with the fuel filter replacement.

here are guides to help us fix the problem:

https://www.2carpros.com/articles/engine-backfires-while-running

and

https://www.2carpros.com/articles/how-to-tune-up-a-car-engine

Gap .................... 0.8 mm (0.031 in)

Check out the images (below). Let us know what happens and please upload pictures or videos of the problem so we can see what's going on.
Aug 2, 2023 at 7:00 PM
Advertisement