I have a 2000 GMC Yukon 2wd, 135,000 miles w/ 4.8L and I'm easy on the accelerator with flat roads and no towing. Live in Naples FL so temp usually in the 80s year round.

Averaging 13 mpg around town in mostly light traffic. Again, easy on the accelerator. Read thru the forum for last hour (I really need to get to work!) and see various threads on similar subjects stating the front O2 sensor (wherever that is) can lead to poor gas mileage. Replaced the plugs w/Platinums 2 years ago. Looking for help in increasing this poor MPG. I'm assuming that 13 mpg is indeed poor based upon above stats. Correct? I can't truly remember but thought I was getting closer to 17 mpg around town a few years ago.

Have also noticed that my white concrete driveway when wet shows some sort of "whiter white" discoloring. This is not my oil leek (Rear main seal leaking just a bit). Am wondering if I somehow have a slow gas leak that I don't see and it only shows up when the concrete is wet?

Last thing, my gas guage has worked erratically for last 6 months. Dealer indicates probably cause is pressure build-up (?) on the sensor inside the gas tank and $500 to fix that so I refused and just fill up every 240 miles.

Separate subject, neither of the 2 back windows work anymore. Took one apart and the plastic mechanism containing the strapping is shredding it. Tried to re-pack the strapping into the motor but failed 1st time out of the gate. Can I buy new strapping on eBay or do I need to replace entire mechanism? Is it relatively cheap and easy to replace? Thanks on this too!

Happy to be here! Wish I could afford to sell this but not in the cards.

Will

Welcome to AF, you need window regulators #1. Second any fuel leak anywhere around the truck would leave an unmistakeable odor. A full scan looking at fuel trims and sensor activity would reveal any issue with that may affect mileage. Dirty injectors another possibility.. A bottle of Chevron Techron may help.

Max, good idea w/the Techron. No gas smell at all so that's probably out. Talked to my brother who says you can cross circuit the OMB II with a batter cable to retrieve the codes? I'm a bit dubious about this but he's looking up the procedure for me. Thoughts on this?

BTW, when I do a tune up on this vehicle, is their a distributor cap or anything like that that needs to be replaced? I thought that when electronic ignissions were invented that points went out the door and didn't need to be replaced anymore.

The cap and rotor should go at 75-100k, forget touching the cables!! It must be properly scanned, no other way here.

The cap and rotor should go at 75-100k, forget touching the cables!! It must be properly scanned, no other way here.


The 4.8 has a cap and rotor???

2000 was not coil on plug ign.

2000 was not coil on plug ign.

That's interesting. So did this apply to the 5.3 as well?
I have a 01 Yukon 5.3 so I was just assuming both sizes had the coil on plug from day one.


What is the main advantage? Appreciate the feedback!