LouieM

Every time I fill up my 2007 coupe the fuel gauge acts schizophrenic for the rest of the day. After filling it to the top, the gauge reads maybe half full, accompanied by a gong and text warning that the car is low on fuel. Then the needle drifts up to Full over the next few minutes. Then if might suddenly swing to Empty with a Check Gauges text. The next day everything is fine. This can't be unique to my dear, but is it common with any of you guys?

SixAddict

No. Sounds like one of your sender units going bad.

HBsurfer

Never happens to my 2007. Add a bottle of Techron to your next fill up. I may free up the sending unit.
I do this a couple of time each year and so far, no fuel system problems.

Iceaxe

^^^This^^^

And if that doesn't solve the problem try a second bottle on the next fill up as it can take a little time to work. I've also had good luck using Lucas Fuel Injection Cleaner with stuck sending units.

Sometimes the above solutions work and sometimes they don't. The plus side is it's easy and cheap to try.

YMMV

LouieM

Thanks for the suggestions. I have kept Techron in the tank most of the time for the past few years, but it didn't cure the issue. I'll try the Lucas juice to see if that works.
I'd like to hear from someone who had the problem and cured it without a mechanical repair, which would be hideously expensive considering how deeply the gas tank is buried.

sonnysucks

There is no trick, there is build up or corrosion on the sending unit... i think it's the drivers side is the first 1/2 of the tank and the passenger the second 1/2 of tank? I've had no fuel reading down through both, no fuel reading then 1/2 tank when it hits the second and i've had it not working then just work, then just stop again. I've used techron and seafoam and i even run ethanol primarily... it's just a bad sending unit.

Landru

Sending unit's shot, remember we're talking about an '07.
Pretty good it lasted this long, actually.
Dropping tanks = beaucoup labor hours, so be damned sure to replace both units.
One member replaced only one and sure enough a few weeks later, other failed.
Don't be that guy.

ssg10587

Yes, seems to be a common issue with C6s. My 05 usually takes about an hour to synchronize. Techron is really your best bet. It definitely improved mine but didn't solve it.

LouieM

Yup, time for Techron again. Those fuel senders are never coming out if I have to pay for it.

joliett

My gauge too...just for about 10 miles and then back to normal until the next fill up. BG44K...much stronger than Techron....it keeps a handle on the problem, sometimes the gauge works even after fill up.
I'll wait until the fuel gauge completely fails before replacing it. ENJOY!

Dano523

Worn sending unit swiper arm pads, and not amount of techron/any other cleaning type chemical is going to solve that problem,

The short bus version, tank needs to be dropped to have the fuel level sending unit replaced.

Just skip to 1:20 to see the worn swiper arms.

LouieM

I suspect you're right; a mechanical fault in the sending unit, but hopefully not. The JPG you sent doesn't show anything useful as far as I can tell.

Dano523

Linked wrong link, but have corrected it in my post above.

LouieM

Thanks very much for the re-post. A very useful video that explains the problem well.

BluegrassMotorsport

Funny you posted this - the exact same thing began happening to me today. Filled my car up leaving Rod Run in TN and as soon as I started it, I got the low fuel warning and the needle dropped. Then it danced all over for a few miles and the check engine light came on.

I stopped for lunch just a few miles down the road and read through some threads on the Forum to see what's happening. Most everyone reported that the problem sorts itself out after the first couple gallons are used. Sure enough, mine started working fine after a while on the highway. I was relieved to see that it's a relatively simple fix in the short term. I bought the Techron when I got home and filled the tank back up. Stopped at Advanced for a code read just to make sure it's for the same issue. Sure enough - fuel system error. I had them wipe the engine light and watched my gauge dance again all the way home.

This Forum is a wealth of knowledge and I'm forever grateful for it. It's saved me a fortune in money and worry in the short time I've owned my car. Now I'm sitting here trying not to dread replacing the sending unit eventually...

owc6

Nothing says in the worst case that you have to replace the sending unit. It's not cheap ($2000-40000) depending on who does it. You can just use the trip ODO, and if you have any recurring CELs, you can have them tuned out.

The C5, C6, and C7 have this problem. I wonder if the C8 will too?

If they are still using silver contacts, it absolutely will be a problem. Probably right after warranties run out, just like at least the last three generations.

Use a bottle of Techron every oil change even if you don't have symptoms. In my experience if you own your car long enough, eventually the fuel level sensor/sender will fail.

Scuba Ghost

No problem with my '13.

Csr24gordo

No! Never had this issue.

Turbo6TA

Your being too impatient .... Don't worry, give it a little more time and you will have this issue.

joeking

I have an 05 and never had a problem. I do put a jug of Techron in it once or twice a year and always during the winter storage months. Never had a problem with this on two C-5's which were notorious for having fuel gauge problems.