Okay, so when I say terrible, I mean terrible. I get maybe 10mpg when I baby my blazer. It has 94,000 miles on the original plugs, fuel filter, etc. I plan on swapping plugs, fuel filter, and a new air filter when I get paid. My question is, what else (regular maintenece wise) do I need to do that could be adversely affecting my gas mileage? What does my charcoal canister filter do and should it be changed as well??

 

Your charcoal canister collects fuel vapors and fumes and converts it to combustable material I believe.
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change your O2 sensors as well...

 

I would start with a general tune up consisting of plugs, wires, cap and rotor. Change out the plugs after doing a seafoam treatment (also plan on an oil change). The fuel and air filters wouldn't be a bad thing to change either.

If you continue to have poor fuel mileage, then you may want to look into changing out the upstream O2 sensors (the ones closest to the exhaust manifolds on either side of the engine).

 

what is seafoam and how do I do it? also, how easy is the cap and rotor change? I think im gonna start with filters, plugs, and wires and work from there....

 

Seafoam is liquid stuff you pour into the engine, just follow the directions on the bottle.

The cap an rotor change is easy, but you'll need a small Torx bit to take off the distributor cap (at least I do on my '96).

You could also have a bad Fuel Pressure Regulator that is leaking fuel into the intake manifold, thus causing excessive fuel to be consumed by the engine with no benefit of the fuel to mileage conversion process on a normally functioning engine. Just my 2 cents worth.

 

so what brands should i stay away from? I hear people knock Bosch, but I had bosh +4 plugs and bosch wires in my last vehicle and they worked great. Should I just replace with ac delco or what? I can't affor to go to iridium plugs or anything so keep budget in mind. Which is best?

 

For plugs, AC Delco or NGK double platinum. For wires... I prefer the Belden Premium wires from Napa. Lifetime warranty!