very bad gas mileage

Asked by Jan 09, 2011 at 08:03 PM about the 2003 Chevrolet Blazer 4 Door LS 4WD

Question type: Maintenance & Repair

I have owned my Blazer for almost two years, just had a major tune-up, replaced wires & plugs w/double platinum, rotor and cap, fuel and air filter.  Gas mileage went from 16mpg to just over 12mpg.  It runs smoothly, has good pick up, idles a little rough as it always has.  The mechanic said it was in bad need of a tune-up as he inspected parts removed.  I thought for sure it would increase the mpg, not decrease.  The cost at the gas pump is killing me!

10 Answers

230

I have the exact problem did major tuneup with all parts replaced as anniegirl replace and getting 12 miles to the gallon now also. Anyone have any ideas?

23 of 23 people found this helpful.
4,785

is it possible that your fuel injectors could be leaking also may want to check to make sure you have proper tire pressure

5 of 5 people found this helpful.
7,325

possibly could have sometihng to do with the winter gas mixtures. ive lost about 3 mpg because of that.

3 of 3 people found this helpful.
55

it could have the same problem mine has .i have a 94 blazer and just posted a question about my injectors spraying to much fuel and now its just flooding out with out starting at all.when its running does the exhaust smell really rich of fuel ?

5 of 5 people found this helpful.
115

my nieghbor has a 97 blazer he recomends k&n air filter with a pick up of bout 3-4 mpg....and he averages around 16...hope to help..

3 of 3 people found this helpful.
1,805

Check all vacuum lines, and re-check all of the plug gaps. I would also recommend using this type of gapper. http://www.sears.com/shc/s/p_10153_12605_00994133000P?mv=rr&i_cntr=1305659742184 Much more acurate and less chance of damaging the plug while gapping.

2 of 2 people found this helpful.
25

my 94 did the same thing, the spider under the intake was bad. @ 1st, it wasnt, the longer it went, the more i could smell gas.

2 of 2 people found this helpful.
60

Hi if your idle is a little rough after checking leads and plugs try checking the EGR valve just behind the thomastat on top at the front of the engine some times they can get a bit of carbon in them and they dont shut off completley ,,or they can just not work ,,we live in the hills in NZ and after tweeking everything I can the best I can get is 17 mpg US ,,these are a heavy little vehicle and could of used a V8,,,

6 of 6 people found this helpful.
70

These Chevy engines suffer from a leaky intake manifold gasket on the from driver's side corner. I redid mine and gas mileage finally went way up! Check for vacuum leaks too. Very important.

7 of 7 people found this helpful.
30

also the temp sensor it acks as a choke an also the number 17 wire comming of the ecm mine went from 18miles to 6 miles replaced temp sensor an know it back to 18

3 of 3 people found this helpful.

Your Answer

Add photo

Related Questions

  • very bad gas mileage 10 answers

    I have owned my Blazer for almost two years, just had a major tune-up, replaced wires & plugs w/double platinum, rotor and cap, fuel and air filter. Gas mileage went from 16mpg to just over 12mpg. I...

    2003 Chevrolet Blazer 4 Door LS 4WD

    -

    Maintenance & Repair

  • very bad gas milesage 2 answers

    I have owned my Blazer for almost two years and had a major tune up recently: wires and plugs replaced w/double plat, cap & rotor, fuel and air filter. The mechanic said that it was in real need of ...

    2003 Chevrolet Blazer LS ZR2 4WD

    -

    Maintenance & Repair

  • stuck gas gauges 1 answer

    i put gas in it 2 times and the gas gauge is stuck right above the E.

    1999 Chevrolet Blazer 4 Door LS

    -

    Maintenance & Repair

  • bad hitch any ideas? 2 answers

    My 2000 blazer with 4.3 vortec has a bad hitch to it when its cold, but when the truck warms up it runs like a top, It almost acts like its losing fire but its has great fire, I have been told its m...

    Chevrolet Blazer

    -

    Maintenance & Repair

  • Gas leak at fuel filter 1 answer

    98 Chevy blazer. Leaking gas on snap on side of fuel filter. I disconnected and tried to reconnect but didn't fix. Gas pouring out..I disconnected and seen orange ring on snap side on hose. And a ...

    1998 Chevrolet Blazer 4 Door LS

    -

    Maintenance & Repair

Blazer

Looking for a Used Blazer in your area?

CarGurus has 1,188 nationwide Blazer listings starting at $1,820.

ZIP:

Search Chevrolet Blazer Questions

Chevrolet Blazer Experts

#1 Andrew Olsen
Andrew Olsen
Reputation 1,990
#2 yetilikesbeer
yetilikesbeer
Reputation 1,300
#3 Rowefast
Rowefast
Reputation 1,030
View All

Related Models For Sale

Used Chevrolet TrailBlazer
96 Great Deals out of 4,752 listings starting at $999
Used Chevrolet Tahoe
559 Great Deals out of 31,371 listings starting at $1,500
Used Chevrolet S-10
5 Great Deals out of 1,311 listings starting at $2,400
Used GMC Jimmy
274 listings starting at $2,495
Used Chevrolet Silverado 1500
1,773 Great Deals out of 181,200 listings starting at $250
Used Ford Explorer
928 Great Deals out of 70,251 listings starting at $997
Used Ford F-150
2,055 Great Deals out of 207,336 listings starting at $1,499
Used Chevrolet Camaro
243 Great Deals out of 31,194 listings starting at $369
Used Jeep Grand Cherokee
1,024 Great Deals out of 72,253 listings starting at $700
Used Chevrolet Colorado
242 Great Deals out of 24,816 listings starting at $2,499
Used Chevrolet Suburban
299 Great Deals out of 19,514 listings starting at $1,800
Used Ford Mustang
541 Great Deals out of 45,846 listings starting at $1,999
Used Jeep Wrangler
260 Great Deals out of 16,543 listings starting at $2,590

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.