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That is really poor. I live in the Appalachian Mountains and I drive all around them with 2" lift and 31 A/T's, and average 18 mpg. When going to town and back with a little mountain mixed in I get 20. And this is uphill-at 30 mph-at-3000 rpm-mountain terrain. Dunno how all you guys get that low of fuel economy. And also, going too slow and keeping below 2000 rpm can be bad, the 96 and up blazers had their power curve changed, and if you keep too low you never get in the effective power band. That causes your engine to struggle a bit and doesnt get into OD as quick. There is an art to it, but it is like running a heavy truck with a small engine, just works too hard to get good MPG.
New Member
Joined: Sep 2009
Posts: 75
From: Kitchener, Ontario, Canada
99 GMC Jimmy all stock and never been tuned up in the 3 years I've owned it. 3.42 gears with the stock tires and the NV236 Auto 4WD and I get around 18mpg mostly city and closer to 20mpg if I mix in some highway driving. Truck now has 308,000 kms on it.
New Member
Joined: Apr 2010
Posts: 6
I would Love to know how to increase my Fuel Economy from 13.5 on my Personal 2000 Blazer LT with American Racing Rims & bigger then normal tires. In fact, at first the tires were so big that when I drove back to the woods o my In-Laws Farm, the Truck would bottom out and the trim would catch & has sliced my tires very badly. I thought I needed a lift kit, but could only find ones for my rear tires, with which I had no problems. So luckily, my Father-in-law knows a cheap mechanic near Union Bridge, MD & I asked him to see what he could do and he somehow adjusted the front of my truck up 2". The Funny part was that he said that I would now have a rough ride, but I honestly have not felt a difference.
Anyway, my Work Blazer gets 13.5 mpg as well, so I figured it is the truck, until a guy I work with buys a slightly newer truck & it gets 20mpg, of which, I just do not believe.
Anyway, my Work Blazer gets 13.5 mpg as well, so I figured it is the truck, until a guy I work with buys a slightly newer truck & it gets 20mpg, of which, I just do not believe.
power programmer? factory is like 14city/19hwy right? i use to 
New Member
Joined: Mar 2011
Posts: 3
From: Dover DE
"Ant" that's a good question. I just recently ran seafoam through my 04 and went from consistantly mid 16's to mid 19's on my last all highway trip
New Member
Joined: Apr 2010
Posts: 6
That is really poor. I live in the Appalachian Mountains and I drive all around them with 2" lift and 31 A/T's, and average 18 mpg. When going to town and back with a little mountain mixed in I get 20. And this is uphill-at 30 mph-at-3000 rpm-mountain terrain. Dunno how all you guys get that low of fuel economy. And also, going too slow and keeping below 2000 rpm can be bad, the 96 and up blazers had their power curve changed, and if you keep too low you never get in the effective power band. That causes your engine to struggle a bit and doesnt get into OD as quick. There is an art to it, but it is like running a heavy truck with a small engine, just works too hard to get good MPG.
I'm glade for those of you that get 18mpg and better, but jealous because everything I have tried from Super Tuneups to Gear & Transmission Service & only get 13.5mpg no matter what. I have a 2000 LT 4x4 & Auto 4x4 that I just checked if it worked today in the rain & it did kick the Front tires right in, with 15" big tires on Baja Rims & my front Struts jack up some to keep my tires from getting cut by the wheel trim. I just changed my 4x4 differential Gear Oil & what came outta there looked watery with flecks of metal & smelled like Cat pee. I intend to do the rear differential soon along with the rear of the transmission if that area uses gear oil.
Anyway, I would love to know how to improve my mileage, as mentioned above, no matter how I drive it always ends up at 13.5 mpg. I use reg fuel and the idle generally puts at 650rpm's. Now on the other Hand, this Truck has Sport Power and can get away from me if not careful, which is surprising.
I'll finish with this, in that I drove an Astro Van loaded to the max with tools and it had the 4.3 & no matter what I did or how I drove, that Van got 21mpg all the time. Go Figure!
Any idea's appreciated!
New Member
Joined: Mar 2011
Posts: 3
From: Dover DE
It is an internal engine cleaner, you can add it to the fuel tank, the crank case and through a vaccum line to clean the upper cylinders 
Sea Foam Sales Company
Sea Foam Sales Company
Senior Member
Joined: Oct 2010
Posts: 647
From: West-Central MA
Keep in mind - those driving daily at high altitudes are going to get better mileage than those at sea level. 5k feet and above really makes a big difference.
High altitude = less air ... computer compensates by backing off fuel. But, with that, you also get MUCH less power. Carbed vehicles will just get boggy, & flat ... and mileage probably worse.
My ol' man's Duramax got 22 mpg up in Flagstaff, AZ (over 5k feet), but never better than 17 back home. Different animal, but you get the idea.
High altitude = less air ... computer compensates by backing off fuel. But, with that, you also get MUCH less power. Carbed vehicles will just get boggy, & flat ... and mileage probably worse.
My ol' man's Duramax got 22 mpg up in Flagstaff, AZ (over 5k feet), but never better than 17 back home. Different animal, but you get the idea.