ShovelMan

How is that possible? I have a 3.8L bird and lately it has been burning holes in my wallet.

I buy the parts and ask my dad to kindly install them. Summer here in Texas is hot and under my hood, the engine gets hotter. No gasket issues here.

The Mighty Texan

iTrader: (4)

Need alot more info, are you using the gauge or are you calculating it yourself, does the engine have any probles or codes? Poor performance? Does it reach operating temp or stay too cold or start getting warm? Burning rich or gas smell? Surging idle, ect. If its none of that check the lines and tank for a leak.

Crimsonnaire

iTrader: (1)

Siphon thief?

ShovelMan

Nope. I keep my gas tank under lock and key.

I have been getting SES codes. The fuel pump may be out, misfiring cylinder, bad O2 sensor and non-purge something.

Any of those?

wssix99

iTrader: (5)

This is a phenomena that comes and goes. Funny - This problem only happens when gas prices are high....

Before you get paranoid, you need to accurately measure your mileage in city and highway driving. You can not do this by reading the gauge on the cluster! The only way to do it is to fill up your tank, drive, fill it up again and then calculate mileage off of the gallons reading on the pump.

ShovelMan

I am just going to fill up. Drive on the highway until the car stops from no gas. all while the trip meter is set to 0

cemlsx

and do keep in mind that our fuel gauges are not the best , mine will take the same amount to fill up whether its at 3 quarters and sometimes even almost half .. they're wacky things ..

KevinR

What is the code exactly? A bad 02 sensor? If it's throwing a code for a bad 02, then I would almost bet that's what your problem is.

ShovelMan

well my fuel pump went bad and I am going to replace it.

LS6427

iTrader: (2)

Unless you have a leak..........only failing 02 sensors will kill your gas mileage "out-of-nowhere".

Misfires also come with failing 02 sensors. And I'm talking about 02 sensors that still work, and might work for another year, but they are on a downward spiral and will keep making the engine run richer and richer.

.

ShovelMan

can the fuel pump do this? mine went bad.

LS6427

iTrader: (2)

I don't see how a failing fuel pump can cause your gas mileage to drop off like that. 100 miles from a half tank....thats wacked. If the fuel pump was leaking it would leak right back into the gas tank. If the pump were failing real bad and making the engine run badly because the pressure was way down you would probably stop driving it because it would want to stall or have horrible power output.

So I'd say NO.....

.

ShovelMan

But anyway, the fuel pump did go bad. You said that a failing fuel pump wont cause bad mileage. Just a side-comment thing: it failed. Checked that valve and no gas. Gas is still on half.

Furthermore, the fuel pump never made a sound when I turned the key.

The Mighty Texan

iTrader: (4)

You need to slow down and start with the basics man. Ok, you say your fuel pump is bad, fix it than if you are certain and if you think that is the problem. Since you aren't providing much information i'm assuming you have most of this figured out already, what are you asking exactly?

HAZ-Matt

iTrader: (8)

I would offer one more piece of advice. Please stop making a bunch of new threads because it gets hard to follow a bunch of bits and pieces. You have another thread a little ways down that says you figured out your fuel pump was dying. It is a lot easier for us to help you when everything is listed in one place.

Also, if you can list the exact code numbers that would be of help.

I somewhat agree with above that O2 errors can cause poor fuel economy and also missing, but if the O2 is way out the car should go back into open loop.

At any rate, the last code sounds like an EVAP code since that is one of the few with purge in the code, as far as I remember.

PrototypE

I suggest you should keep in mind GM fuel level sensors are a known problem, especially on truck models, but we have the same fuel level sensor they do in the tank.

If you inspect the pump module closely, you'll see that there are 3 'fingers' that make direct contact with the level sensor on the opposite end of the float rod, on the side of the fuel pump modular assembly. Those 'fingers' tend to break off, or wear down, causing intermittent or inaccurate operation of your fuel gauge, possibly setting a DTC. The details you give are a little sparse, Is this an excessive fuel consumption issue or a perceived gauge issue?