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Discussion Starter #1
i have run out of gas 2 times in the past month because the fuel gauge is reading wrong... ill run out of gas when it says 1/4 of gas left in the tank... im out of warrenty because i have 59000 on the motor.... any suggesstions as to what may be wrong?
 

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Is it an '03?

If so, I think a couple of us are having the same problem. I'm gonna have mine serviced for the same thing. I will call the dealership today and ask. I'm supposed to have my car serviced, but I haven't had the time! Work is killing me!:thepan:
 

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08 Platinum Escalade, 08 CTS, 01 TransAm WS6, 07 SolsticeGXP
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This used to happen on my Grand Am.
I knew that Pontiacs were known for this type of thing.
My CTS is fine.
Seems like a relatively easy adjustment.

When my sister borrowed the Grand Am, she ran out gas, and when my mother-in-law borrowed it, she also ran out of gas.

It's a great trick!

M
 

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Michael 514 said:
When my sister borrowed the Grand Am, she ran out gas, and when my mother-in-law borrowed it, she also ran out of gas.
thats hilarious...i suppose thats a great tactic to get people to stop borrowing your car! :p
 

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my dodge ram use to do that...but that thing took half a tank to simply turn it on! I myself ran out of gas 3 times...I carried a little gas tank with me at all times...:helpless:

I made an apointment to have my car looked at on monday...I can keep you posted if you wish...
 

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What brand of gas do you use? Sometimes with the cheaper gas it creates a sludge that creates problems for the sending unit and fuel pump. I have had this happen with ARCO gas in the early 90's.
Do you hear any noise from the fuel tank?
 

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'05 CTS Luxury
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Dump some Marvel Mystery Oil into your gas tank next time you fill up. It will dissolve any varnish, etc. that's built up. It's great stuff.
 

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Discussion Starter #9
yeah, i have a 2003, so im guessing its a problem with this model... i use regular mobil gas so its not like some mom and pop store gas (but i do use regular unleaded... should i run a higher octane?) im going to try the marvel stuff and see if that takes care of it, i also know i need a new fuel filter so maybe thats an issue that may be affecting my troubles...

thanks for the help

andy
 

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2017 CTS-V
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xtuffycorex said:
yeah, i have a 2003, so im guessing its a problem with this model... i use regular mobil gas so its not like some mom and pop store gas (but i do use regular unleaded... should i run a higher octane?) im going to try the marvel stuff and see if that takes care of it, i also know i need a new fuel filter so maybe thats an issue that may be affecting my troubles...

thanks for the help

andy
Your 2003 is supposed to run on premium (91 octane or higher) gas. This shouldn't be causing your gas problem though. I have not had this problem with my 03.
 

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I normally set my trip odometer to zero everytime I top-off. When I get about 300 miles, I stop for gas again just to make sure i won't run out.
 

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You guys are all 03's? I've got an 05' and my guage is faulty too. I ran out of gas last night on the highway when my tank read 1/4.

Before I filled it up last week, it said it was totally empty, I looked at my trip (i always keep track of km's) and I had only gotten 310 km's to one tank!!! Thats less than 190 miles!! I couldn't believe it, but the last several days, I've noticed its wacky, always varying every time I turn the car on!! Sometimes a half tank, sometimes 3/4, sometimes 1/4. Mines going in for new rear diff, hub bearings, and accessory belts next week, so I'm gonna get them to check the gas guage.
 

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I hope I don't freak anybody out here but I'll give you a little information on your fuel systems on CTS that may blow your mind.

First of all, technically the CTS has 2 fuel tanks, even though it is one tank.
There is a hump in the middle of the tank because there has to be some room for the exhaust to fit under the tank. Instead of making two small tanks they made one big one. Obviously the fluid sits in the bottom of the tank so the hump separates it into two areas. It has two fuel senders but only one pump. The main fuel pump has a small tube that is fed by the fuel pump and it sends fuel over to the opposite side of the tank through what is called a "jet pump". The jet pump is basically small orifice that is set inside a venturi type device and as the fuel comes squirting through it creates a low pressure area, this causes fuel to be drawn up and the jet and additional fuel is transferred via another tube back to the side of the tank with the fuel pump in it. This action is constant.

This system is actually a variant of the system that they have been using on Corvette since '97, with the difference being that Corvette actually has 2 separate tanks due to the size of the tunnel for the powertrain.

What happens is that the pump constantly runs and transfers fuel from one side to the side with the pump on it. While this happens a fuel level sensor on each side sends a reading to a computer and the computer calculates the fuel level based on the combined readings. If one of the sensors is bad, or the jet pump doesn't operate properly due to whatever reason you'll end up with problems. The computer is programmed to notice failures in this system and if it does it will make the fuel gage go to E and turn on a Check Engine Lamp. The reason it does this is actually because the fuel level sensors are considered an emissions device. The computer must know the fuel level in the tank in order to run a diagnostic on the EVAP system, but that is another story.
The problem with the diagnostics is that they require a very long drive in order for the computer to notice the failure. I think on Corvette it was like 150 miles. If you do lots of in town stop and go driving it's doubtful that this diagnostic would ever run.

That being said... I think the problem you may be up against is a fuel transfer problem. The secondary tank will probably register about 1/4 while the "primary" will be empty. With gas on one side of the tank that can't get to the other you'd just run out of fuel even though the computer sees gas in the tank.
I'll see if I can find an illustration to show you.
It's a fairly complicated system that some shops may not have had experience with so be patient. It's not much fun to get those tanks out either.

Take them in with not much fuel in them, I have seen dealers not do work because they couldn't handle the fuel while they worked on the tank, you have to drain it first then pull it out.

We have a joke in the business about how people always fill their tanks before they bring them in for us to remove them.

Looking for pictures.....
 

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Crud, I can't find one.
I know my latest magazine that I got from GM has a picture of it right on the cover but I can't access it online from home.
Maybe on Monday I'll see if I can get to it to show you a photo.
 

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I have a 05' CTS. Just got a recall letter today on the Fuel Low Level problem.
The letter is stating that a software calibration change will correct the problem, and the fix will be ready in April 05'.:werd:
Wow... I was planning my first drive to New York.
 

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Update:

Well after an oil change and new rear axle :eek: ! I guess they gave up on my list of items. The dealership said they couldn't recreate the issue with the gas gauge :tisk: ... don't they know by now that now i'm gonna take it back in with the above mentioned bulletin, lets see what they say now?

Oh, they also said the rough idle issue is a characteristic of the 03 CTS :bomb: aint that about a #%$#@!
 

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2003 3.2L Luxury Raven Black
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I too have an 03 CTS and noticed the gas gauge fluctuates but the bulliten states for 04 - 05 CTS's?
As fare as the rough idle I brought my CTS in for this problem and they had some sort of bulliten regarding this and they downloaded something to the cars computer and I have noticed a significant change for the better when idle.
Regarding the gas Octane (Premium) the manual says recomended only for premium and that putting the lower gas grade is still OK to do.
 

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just lou said:
I received the recall notice today. It says until it's fixed 4/06, not to let the gas tank go below 1/4.
I need to wait until my rep gets back from the holidays to ask if this applies to 03's.

Oh, BTW, I only use 93 octane gas...maybe I should put in a fuel injector cleaner for the rough idle. The dealer said that my car has the latest updates already...
 
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