I have a 1998 Blazer 4.3 with 75k miles on it and took it in for a tune up and the gas mileage is worse now than before the tune up. The guy replace all filters, plugs, wires, cap & rotor and when we took it back to try to find out what was going on he replace the fuel pump and 1200.00 later we're getting 11mpg. don't think the gas mileage was ever that bad.
Any thoughts????

 

Is the engine running differently than before the tune-up? If so, in what ways? What was the MPG prior to the tune? More info would help out.

 

Prior to the tune up the mpg was around 22 and it's now around 11-12. Before the tune up it had a more noticeable miss which is still there but less prominent.

 

This question is a joke, right?

You were getting 22 mpg.
You get a tune up.
Now you're getting 11 mpg.
You ask if that's normal mpg.
Which would make your pre tune-up mileage.........what?????

 

Actually Ted no it wasn't a joke and I guess you have no advice..
Thanks anyway!

 

I would ask what brand were the parts he put in place of the originals. AC Delco Platinum plugs seem to work best for our trucks, also they need to be gapped at .60 inches. Also from what I hear AC Delco cap and rotor is the way to go. I would ask if the fuel filter was replaced and if not probably replace that. Otherwise I would check the radatior fluid and thermostat. Other than that, make sure the MAF sensor, IAC, and EGR valve should be cleaned. Hope this helps.

 

You didn't ask for advice...you asked if it was normal mpg.

Focus on things that would cause an over rich condition, like coolant temp sensor, O2S or leaking injectors. If you had a miss, was it setting a code? OBD2 vehicles should.

Have you brought it back with the low mpg complaint? If yes, time to find a mechanic who knows cars a little better.

Is someone different driving it? Is someone starting it and letting it cool down for 20 minutes before driving it?

 

check and and see if your 4wheel drive is engaged if it is that whould reduce your gas milage alot. doing a slow sharp turn (steering wheel turned all the way) on pavemet if you feel the the truck hopping very heavy vibration 4x4 most likely engaged or go find some loss dirt and try spining the tires a little bit while you or a buddy watchs your front tire to see if they spin. other then that man if you already tried what everyone else told ya then go punch your mechanic in the fast knock over a oil drum and walk out.

 

Thanks Lenny, I'll have to do some serious research because unfortunately the mechanic that did the work is not cooperating with us and I'm not the one under the hood. Come to think of it way back before the tune up was ever done there was a problem with it running hot all the time and he eventually changed the thermostat and fix the temp problem. Doubt he's using AC Delco parts, but I'll have to dig up some receipts and see what I can find.
Nobody different has been driving it and there is no 4 wheel drive. Even around town we were getting 16-18 mpg. Something is definitely not right.
Thanks for your help..

 

lol i think someone syphoned your gas. But seriously, how many times have you refilled and checked your gas mileage?