mjohnson68

Well I have owned my C5 for 7 years and have tried just about every chemical on the market to fix the gas gauge issue. It seems that my issue is at any level past 1/2 tank the gauge is broke. When I fill it up it only shows 7/8's and works for about 15 miles. After that it drops to empty until I reach the 1/2 tank area when it starts to work again.

Any idea on which sender could be causing this? Or am I going to need to replace both of them?

I have lived with this for 7 years and just kept track of mileage but I am thinking about selling the car and I know the next owner is not going to feel the same way.

Mike.

jackthelad

Have you ever had the gas gauge "crash to zero" fix done? It's a TSB that involves a computer reflash from the dealer. Though mostly people who have that problem find turning the car off and then restarting brings the gas gauge back for a while at least.

Lots of threads on here re gas gauge issues.

mike_engr

I'd be curious to know what you learn about the TSB. For instance, how much do dealers charge (or supposed to charge, if anything) to do the TSB computer flash?

My 2001 had gas gage problems when I got it about 14 months ago and I ran out of gas twice before I finally realized what was happening by reading this forum! Thanks forum!
But it has been fine now almost a year with a few Techtron treatments, CITCO Prem gas, and more frequent driving than the previous owner(s)!
But maybe I should have the TSB reflash done anyway. So I wonder what it should cost, and does the flash "fix" anything else (for a 2001 vert)....
Any risks? I'm pretty sure the car doesn't have a prior "tune" to lose...

jackthelad

Not sure as mine was done when the car was in for something else. I would call a dealer and ask.

zachaeous

I had this problem with my 2001. I tried the chemical into the tank and it had little results. I also went to the dealership and the TSB done and still had the problem. I researched the problem here on the forum and narrowed the problem down to the right side jet pump. I replaced the jet pump and problem was taken care of. After looking at the sending unit that I took out it was definitely not making good contact. I do believe that you could clean the contact area and be good to go, without having to replace. It is not too bad a job on the earlier cars that come out the bottom. Good luck

The dealership charged me $25.00 for the reflash and it took about 30 minutes to complete.

mike_engr

Thanks Zach, yes there are certainly sometimes issues with the Jet Pump - - - if you run out of gas and it only takes ~9 gal to fill up then you have a Jet Pump problem! !!
If someone's C5 acts like mine (last year) where it took 18+ gallons to fill up when you've run out of Gas (twice), then your JET pump is working fine! I would definitely try the reflash if its only 25 or even $50.... Thanks for the info.

mjohnson68

Yea I did notice that the right side sender seems to be on the bottom. Maybe next time I get low on gas I will try to take it out and see if it can be cleaned. Of course the dealer told me (during my last oil change) that it would cost about 2k for new tanks, senders and labor... LOL...

Bill Curlee

The very FIRST thing that you need to do is read and post the DTCs when the gage errors out and you get the LOW FUEL MESSAGE.

Without turning off the ignition, clear the messages by pressing the RESET button and then follow this procedure. The DTC will tell you which sensor failed and then you can go into the correct tank and replace the correct sensor.

Bill:

READING YOUR Engine Diagnostic Codes



The Diagnostic Display Mode is entered with the following procedure:

1) Turn on the ignition but don't start the engine.
NOTE! You can read the DTCs with the engine running and or driving down the road but it can distract you. BE careful! Some DTCs clear themselves when you turn the ignition OFF!
I always read my DTCs prior to turning OFF the ignition switch. If you have any messages on the DIC,, PRESS RESET until they are gone!

2) Press the RESET button to turn off any warning messages. (i.e. door open, trunk open ect.)
3) Press and hold OPTIONS
4) While holding OPTIONS, press FUEL four times within a 10-second period.


Initially, on-board diagnostics go into an Automatic Mode which shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each. ( i.e. PCM = 4 codes) If none are present in a given module, you will see No More Codes on the display.
There are two kinds of diagnostic codes, Current and History designated with a letter suffix, "C" or "H". A current C code indicates a malfunction is present and active in the module displaying data. A history code indicates a problem existed sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it's potential evidence of a previous problem, now resolved, that was not removed by clearing the codes.
More likely it's an indication of an intermittent malfunction.
Intermittent codes are the most challenging of the diagnostics. An intermittent code may have happened once, may have happened more than once but is inconsistent or may be happening on a regular basis but not at the time the codes are displayed. History codes can also be caused by a current malfunction in a system that is not operating at the time codes are displayed. An example is the rear window defogger which doesn't operate until the Body Control Module detects engine rpm. For history codes set by a module that does not operate with the key on and engine off, a special diagnostic tool called a Scan Tester is necessary to properly diagnose the malfunction.
Once the system has displayed all modules, it goes into the manual mode which allows selection of each module using combinations of Driver Information Center buttons. Manual mode can also be entered during the automatic sequence by pressing any button except English/Metric (E/M). Once the display shows Manual Diagnostics, select a module by pressing the OPTIONS button to go forward or the TRIP button to go back. Once a module is selected, a code is displayed, and if more than one are present; press GAGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase codes in a given module, press and hold the RESET button To reset the codes once in manual mode, press and hold RESET until it displays NO CODES Press OPTIONS to go to the next module. Repeat the steps until you have reset the codes in all the computer modules.
NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this. Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory. If you clear the code/s, and extinguish the Check Engine Light, your emissions status ready will NOT allow you to pass an emissions test until you have completed the required driving cycles.
Once you have the codes, the next question is: What to do with the information?
First, consult the factory service manual. Any serious C5 Do-It-Yourself owner should invest in the Corvette Service Manual of the appropriate model year. The Service Manual is really a requirement if you want to understand and work on your C5. You can GOOGLE the DTC and also find information on it.




Here is very good site that explains the DTCs:


http://www.corvette-web-central.com/C5DTCcode.html


http://www.obd-codes.com/trouble_cod...d-ii-codes.php



Make sure to include the H or C suffix!!

73Corvette

Your simply amazing Mr Bill

mjohnson68

Thanks Bill I will check the codes and see whats up.