I have a 98 s10 blazer that several mechanics incledeing a mechanics teacher have looked at and are at a lost as to what is wrong. It drives good, no codes, everyting checks good, for all apperances is in tip top shape except it has gone from 20 mpg to 8 or 9 or 10 for no reason.Any one ever have this problem?

 

[sm=welcomesign.gif]to the Forum. It's hard to imagine this kind of mileage loss without some other symptoms to go on. How's it running - rough, hesitation, no power at highway speed, etc?

 

Thats the thing,it runs great , no hesitations no nothing, just a really nice running blazer that i love except for ths gas mileage problem. Trying to remember whether it came on suddenly or all at once and honestly can't remember for sure, but I am thinking that it just got alittle low and then lower and then worse over a couple fo weeks

 

How are you calculating the mileage? Is it from the overhead trip meter?

For that large of a drop, you have some significant problems that should manifest themselves... I would start with a tune up if you cannot remember ever doing one (plugs, wires, cap & rotor). Clean the MAF sensor and EGR valve. Clean the throttle body. Check your fuel pressure and make sure that it doesn't drop more than a few PSI when you turn off the key.

Do you have a leaking fuel system?

 

what do your rpm's look like at 70mph? if you have a automatic, maybe you lost a gear. i know it sounds crazy, but just an idea.

 

Check your vacuum on the front transfer case...if it's not good..it will always keep your front axle in gauged (sp)..that can significantly lower gas millage...and won't send a code..

even if your 4wd button works fine...still check it out...

 

Tune up , also check your tire air pressure as well!!!

 

I'd also be interested in seeing how you are calculating the gas mileage...

 

Hi,
I'm not trying to be a smarty or hijack a post here,
but back when cars 6 Volt systems, I admit to "borrowing" a gallon or two of gas from a nerighbor's car or my parents car, and taking so little from a mostly full tank, they never noticed it.
I'm embarassed to admit, as gas was only 23 cents a gallon back then, but I didn't have a job
Just a thought, that a locking gas cap might tell a tale??

 

yea... thats how I fixed my gas mileage problems... My truck got terrible mileage while it was parked at school all week... went to wally-world and got a locking gas cap... I stopped losing gas..