I'm having gas mileage issues....

[cavaliers60]

Yeah, but it's hard to fix something when your income is next to nothing.... I'll get it fixed as soon as I can.

[shortcut]

Are the tires the same brand/type as before? for best economy use tire pressure indicated on the tire not the car.where are you buying gas? GM cars generally don't like BP fuels. try running a tank of premium through it with a bottle of techron injector cleaner before you change the fuel filter that way anything freed up in the tank will be in the old filter not the new one.you should be getting 25+mpg highway even in winter.

[WarrenBlack]

My 99 3.4L is having a hard time with the rough starts and bad mileage too. One thing I can say is its NOT the water pump. If the bearings in your pump are slowing your motor down that much its about to fail andyoull see that soon after you notice the mileage. Ive ruled out plugs, wires, front O2 sensor, map sensor and mass air sensor, and fuel filter. Only things left are fuel pressure regulator, coil pack, or egr valve. Now these parts are a little expensive to be guessing with but my logic tells me its the fuel pressure which would give you bad mileage if too much fuel is being dumped. You may not even smell if if your ECU is adjusting properly to burn off the richness. If I can figure this out Ill repost. Now who can tell my what the fuel pressure is supposed to be so Ill know if I can pull out a normal reading????????