New Member, here, so thanks for reading! Here's my situation. My Baby! My 1997 4X4 Chevy Blazer used to get almost 400 highways miles/tank, about 340 city miles. Now, it gets about 200 miles city. I know she's not new, but that's about a 40% reduction in efficiency. I have replaced the spark plugs, air filter, PCV valve, rotor button and cap, and all three oxygen sensors and still no difference. Any suggestions? Begrdnr@aol.com. Thanks!

 

Wow! That's a big drop..Is it running good? Any kind of symptoms? Missing, rough idle, hard starting, or anything like that to go on. Or maybe some kid in the neighborhood with a rubber hose and a gas can? lol

 

Hey! Use the search feature in this forum-you will find this addressed! But rest easy about your fuel being siphoned;it can't be done as the fuel filler neck is an anti-siphon design that doubles as a roll-over fuel escape lock! Good luck! step 66

 

this is the same problem i having currently. it looks like the fuel spider is my next replacement. over the past 4 months mine has dropped from 18ish-21 highway to 15.5 . lemme know if you figur eout anything.. and ill try to keep you posted on mine.
there is a TON of good information if you search the forums though. i septn about an hr just reading old threads about this same problem.

 

Thanks for reading! OK; here's my situation: I was getting 330-345 miles a tank from my 97 Blazer, 4wd. I had to replace the brain module (odometer and speedometer were going at 50%). She runs fine mechanically, but got 230 miles a tank. I have replaced the spark plugs, cables, rotor button, distributor cap, air filter, pcv valve, fuel filter, and cleaned the EGR valve, mass air flow sensor, replaced all oxygen sensors, and had the fuel system cleaned out (Wal-mart; Pep Boy's machine was broken), and replaced dry-rotted vacuum tubes. After all of that, I now get 245-250 miles a tank. I realize it's an old car, but I had a 95 Blazer that consistently got 330+ miles on a slightly smaller gas tank.
Anyone have any ideas? Begrdnr@aol.com.
Thanks!

 

Did the drop in mileage occur after the PCM ("brain") was replaced? Where did you get the replacement PCM? Was it properly programmed for your truck?

 

*Combined the two threads concerning the same issue. Rather than start a new thread on the same problem (which is against the Forum rules), please continue in the original thread so everybody can follow what has been done.*

 

Include me on this search for lost gas mileage. I even have a new motor, new MPFI spider, new fuel pump, ICM, Ignition Coil, CAT back exhaust, fuel filter and fuel pump relays and I was excited to finally reach 300 miles on one tank of gas. Is it possible we have a need to flash the ECMs