Hey I have some serious gas mileage problems. I can seriously watch my gas gauge drop as I'm driving. I was on like quarter of a tank last night, put 10 bucks in today, which brought it to almost half a tank. I drove about 50 miles today and I'm already on empty.
Any idea or tips as to why my car has such bad gas mileage and how I can improve it would be helpful, otherwise I will be forced to sell this car that I love.
Thanks

 

Are you sure that your gas guage is working correctly? My guage doesn't even come close. I fill mine and within about 50 miles it's showing about a half tank. I just go by my tripometer. I get about 400 miles to a tank. Really though, 10 bucks isn't that much gas either. If you're using the premium that you're supposed to be using, that's about 5 gallons. If your guage is accurate then I would suspect that you need a full tune up and have the O2 sensor replaced.

 

Your fuel filler pipe could be rusted through or gas cap is worn out. When you get gas do you hear a hissing sound when you open it up? If you don't hear anything then you know that your gas tank is not being pressurized and fuel vapor is escaping. I've had my fuel filler pipe replaced because they rust out, it's a recall.

 

Also check to make sure that your charcoal canister is connected, sometimes they come off when you hit a bump or run something over. It's near the front bumper on the passenger side i believe. When i got my car it wasn't even connected.

 

On the SE gauges it say's "Unleaded Only"....what's up with that then?

 

Mine says unleaded only as well. The manual tells you that your car is designed to run on a minimum octane rating of 91, but you can use less than that if you have to. Basically, it tells you that if you want the full performance out of your car and don't want any pinging you have to use the 91 or higher octane.

 

I don't mean to state the obvious, but all cars these days run on "unleaded only", but I think you were just saying that it doesn't say anything else on there. I am pretty sure mine says something right inside the gas door about running 91 octane at least, I'll check on my break at work. I know it says it in the owners manual too.

 

Never really thought about that before...good point . But for now with the gas prices getting insane, i'm getting cleaned everytime I fill up

 

yeah, i get bad gas mileage also, about 200 per tank...when ever i open the cap to fill up the gas tank, i hear a hissing sound, what does that mean??

 

so if im not hearin a noise when i open the cap, what do i do? get a new cap or what?

 

New cap or new filler tube, the filler tube might not have been replaced under the factory recall...check it out...

Brian

 

Another reason for the unleaded only could be that Maximas were sold all over the place, and back when our cars were new, some places still had leaded gas, and in some cases it was only a couple years since a few cars were still being sold without catalysts. The Chrysler K cars in Canada, for example, didn't have a cat, and could run on leaded.

As for your cap hissing, if you go back and read the previous posts, there's one there that mentioned this is normal. As the tank empties, fuel vapours remain in the tank. Modern gas tanks are designed to hold the pressure of fuel vapours so that they do not escape during driving. Fuel vapour is actually a lot more volatile than straight gasoline, as it's already in a gaseous state, mixed with oxygen, and ready to burn. By the time gas gets mixed with air in your engine, and enters the cylinder, the air/fuel mix is pretty much vapour, that's where the power comes from. Gas without proper atomiztation just burns, doesn't explode.

If you're not hearing a hiss, either the cap seal is gone, or like the post above stated, there's a leak in the filler line. Get it checked out sometime, or take a look at it yourself.

 

You know, it is a recall, and I think it applies to all maximas that are driven in areas where they use salt, so I think you could just take it to a dealer and they could fix it for free or at least they could look up the vin number and see if it has been done already. The recall was on the gas filler tube and if it's rusted through, that is where the gas could be leaking out and why there is no pressure in your gas tank. I'm not too sure about the "free" part, but its at least worth checking into.