Bad Gas Mileage [Merged 9-6]

[99GST]

I am still getting some pretty bad gas mileage.

I am only getting about 19.7 mpg with mostly city driving shifting at 4k.
I have already replaced my front O2 sensor and am looking to replace the fuel filter.

I have a 99gst with about 55k miles on it. Should my fuel filter already be bad?

What else should I check or change? I have NKG plugs and Accel wires are on the way.

Thanks,
Nathan

 

[UNSpooled]

I can't believe nobody has mentioned boost leaks yet!!! Pressure test it..anytime my car has ever bogged/sucked gas it always came down to a boost leak.

 

[Defiant]

most people dont see 100% because 100% would be an absence of the plate it self... 100%=no restriction... the throttle plate doesnt just disappear... and also i know im not the only one who sees sub 100% numbers, and i believe its rare for people to see 100% wot, from what ive heard/seen...

You're thinking flow. The % is a measure of position, not flow.

 

[SinEclipse]

what are some causes that give bad gas mileage?

i just got my engine rebuild and i seem to have bad gas mileage. well, i been having it even before the engine was rebuild, but this time i get this bad smell like burnt fuel or something.

 

[Fayt]

I'm having pretty bad MPG too, around 13-15. I also drive hard sometimes (shifting at 6800-7000 ). I'm pretty sure thats why I was. Recently, I've been trying to use no boost when driving in the city to and from places. No idea if its helping yet, I'll get back. No CEL's, bad sensors, new plugs, wires, and air filter. Could it be that my dad filled up my tank with 87 octane and not premium? Theres no knocking, but I have noticed it doesnt run as quick as usual.

 

[SinEclipse]

forgot to mention that there is no cel. also can a bad turbo give bad gas mileage?

 

[zachakagoat]

could be but when was the last time that you changed your fuel filter? If it hasnt been changed in awhile change it and you will notice a MAJOR difference. Also check for boost leaks because if you are having a boost leak you will be losing air that your engine is expecting so you are getting more fuel in there than needed for the mixture of air. My guess is pry the fuel filter though

 

[SinEclipse]

okay this is a noob question, where is the fuel filter located at? also is it easy to change since im still learning how to do lots of things myself.

 

[mitsuman_626]

its located on the firewall

under and to the right of the battery

i'd recommend buying a k&n fuel filter, they're a bit pricey but they're washable and it beats forking out forty bucks a pop every few months.

 

[mitsuman_626]

oh yeah and it's kind of pain in the ass getting your fuel line reconnected.

 

[maynard]

okay this is a noob question, where is the fuel filter located at? also is it easy to change since im still learning how to do lots of things myself.

It's mounted on the firewall close to the battery.

 

[SinEclipse]

thanks for the picture and replies. i'll be fixing all this hopfully by friday.

okay from the look of it how do i remove and change the filter and will fuel be coming out or anything?

 

[99GSXAWDTURBO]

i get rather bad gas milage too, less than 200 miles per tank. my gsx has 100K miles...should i replace the fuel filter?

 

[maynard]

thanks for the picture and replies. i'll be fixing all this hopfully by friday.

okay from the look of it how do i remove and change the filter and will fuel be coming out or anything?

You'll have to remove the rubber fuel line on top, the steel fuel line on the bottom, you're going to lose some gas when you undo the lines. Then I always remove the filter by taking out the 2 bolts that hold the filter bracket. They're the ones with rubber around them. The bracket and filter will come out in one assembly.

 

[maynard]

i get rather bad gas milage too, less than 200 miles per tank. my gsx has 100K miles...should i replace the fuel filter?

If you don't know when it was changed last then YES.

 

[Defiant]

i'd recommend buying a k&n fuel filter, they're a bit pricey but they're washable and it beats forking out forty bucks a pop every few months.

-------------------------------------------WTF

 

[zachakagoat]

I don't know bout yall but all of my fuel filters have only been 10$ from my parts guy. And I've never heard or seen a K&N fuel filter

 

[lov4godgst]

http://www.plymouthlaser.com/fuel.htm

This will show you how to replace a fuel filter.

 

[DSMstatus]

i found that its easy to hold your wrench on the top of the filter then hit the banjo blot with a 1/4 inch impact wrench (lightly) then lay on your back with one arm and a wrench through the wheel well and your other arm and a wrench around by the rear engine roll mount. good luck, its a pain any way you do it.

 

[DSMstatus]

oh yea, dont use the impact to put it back on!

 

[johnalomu#11]

Call Lordco....They have K&N fuel filters for little over $100 and they are washable.

I went with the a Inline fuel filter(which was ment for a boat,you can install it in the back by the gas tank)It has dual line inlets and it right there so it's easier to change.

 

[SinEclipse]

thanks for the link on how to change the fuel filter. will i lose a lot of fuel or will it just be a little coming out and stop since im currently low on fuel and i mean low on fuel.

 

[mokkema]

Ok guys...I think I read correctly but correct me if I am wrong...

Does venting to the atmosphere inhibit bad gas milage?

Between Tuesday morning and wed. night I went through a whole tank

BUUUT, I did drive quite a few miles...but seriously...a whole tank?!?! LoL someone tell me if I gotta get rid of this stupid BOV so I can get some decent milage...

 

[chico904]

Yes. What kind of BOV are you running? You want to get one that recirculates back into your intake. You DO NOT want to vent your BOV . Type in vent and BOV in the search feature and you will see a million reasons why.

 

[amp9211]

Usually when you vent, you end up running rich between shifts. This is what usually causes cars to not run right. How many miles did you drive and how many gallons did you use? This info will help us out in determining if it an unreasonable fuel economy.

 

[washed_up_talon]

venting=bad everything