23rd Sep 2005, 22:03

Sounds like you have I problem. I owned a 2000 GMC Z71 with the 290Hp 5.3L engine. This truck had power to spare! At 35,000mi the rear universal joints failed. At 37,000mi, the trany would make a slight moaning sound in overdrive at low speeds and sometimes slip under acceleration. I had the trany flushed, added new oil (Mobil 1 ATF) and replaced screen filter. This solved the transmission problems. I traded the truck at 67,000mi and enjoyed 19mi/gal highway economy the entire time. I had added dual 2.25" exhaust with K&N, s FIPK set-up. This got me 22mi/gal highway with the tailgate down. I now own a 2002 GMC Z71 with 295Hp 5.3L engine. Same thing; tons of power and great mileage! The rear universals on the '02 went bad at 42,000mi and now, at 45,500mi, the trany is moaning & slipping -time for a transmission service. Fuel economy is at 23mi/gal with a K&N FIPK and 2.5" straight pipes (no muffler).

17th Nov 2006, 08:01

I owned a 2002 GMC Sierra SLE with a 5.3 liter. It got around 20 miles to the gallon and had plenty of power below 2000 rpms. On regular take offs we would run 1500 to 2000 rpms and could start out faster than any other stock vehicle on the road.

19th Dec 2006, 15:57

I own 02 GM Z-71 SLE. At 75000 ks (45000 miles), I replaced left front hub and both universals. E brake cable inside was next followed by low speed fan resistor, now I have oil coming out the tail stock. The so called cup holder in rear of center console won't hold a bottle of water, turn the corner and it falls out. Time to trade it in won't buy another GM.

19th Feb 2007, 12:50

If you didn't like the storage options in the vehicle why did you buy it??? Comparing your 5.3L to your neighbour's 6.0L is pointless. Of course he would have more power! Maybe you do have a problem with your engine. As someone who has worked at a dealership (not GM) the best way to get your vehicle fixed is:

1) Don't diagnose the problem. Simply relay to the service advisor what is happening. Don't suggest parts to change or procedures to do. This forces the technician to do all of the troubleshooting steps.

2) Don't complain about what a piece of crap you own when you are in the dealership. Dealers can adjust your final repair bill and save some money if you aren't in their face the whole time. I've seen it happen. Just be nice to them and stay calm.

30th Apr 2007, 16:09

I have a 2003 GMC 2500 HD which I bought brand new. I averaged 17 mpg on the highway right off the bat. You must replace your fuel filter every 12,000 miles or you will see a major decrease in fuel economy. Fuel pump failed at 30k due to allowing the truck to run on the last 1/4 of the fuel tank. Always keep the truck no less than a quarter tank or you will have fuel pump failure. My experience with G. M customer service was not the best,but this is still a great truck despite $80 a fill up.

6th Mar 2010, 21:42

I have a 2002 GMC Sierra with 130,000 on it, and it runs perfectly, just took it to Vegas and back, and got 18-20 on the highway, I usually get around 16-17 in town. Tranny is strong, and this truck has way more than enough power. I'm very impressed and satisfied. Sorry you got a lemon, never had a problem with GM.

6th Dec 2010, 18:00

Buy a Ford F150, you will have all the power you need along with spacious room, plenty of cup holders that will actually hold your drinks.

I used to be a die hard GM fan, I own a 99 F150 5.4 275,000 miles, my buddy owns 2002 Sierra 5.3 80,000 miles. My truck still has more power than his. He also said he would never buy another GM truck, as far as the comment about taking it to a dealer to diagnose the problem, find a local trustworthy shop in your area. I have been working on vehicles my entire life, dealerships plain and simple, rip off. Every vehicle has its problems; Fords, Chevys, Dodges.

It boils down to what makes you happy, and the F150 does it for me.

17th Apr 2012, 21:54

I'm willing to bet anything that the original poster had a bad map sensor... it explains his lack of power, trans hunting for gears, and poor mileage. They often don't trip the check engine light... Sad that his whole experience was ruined because of a $50 sensor.