Low Fuel Light

[avbump]

HELP...yesterday my C6 low fuel light came on & gauge was indicating empty... tank is FULL...3-4 miles down the road, everything was working a-okay again.

[shalenss]

Originally Posted by avbump

HELP...yesterday my C6 low fuel light came on & gauge was indicating empty... tank is FULL...3-4 miles down the road, everything was working a-okay again.

I think it has something to do Bush and Chenney J/k
I'm no help bro but never happenned to me, if it happens,You might wanna post on C6 forum

[SLPRC5]

It has been a problem with the C5s, not sure about the C6.

[99C5Alan]

A lot of intermittent fuel gage problems have been caused by gas with a high sulfur content. A year or two ago half the mid-west had problems when a large quantity of gas was produced. Some people claim one brand of gas or another is better quality and some people buy Chevron's techron additive and use it to prevent such problems.

My C5 has occasionally shown low gas when it should not have but always corrected itself shortly.

[hamstar]

This problem sometimes happens with C5. I had the similar problem with my C5 several times. With split gas tank, the gages that monitor the gas level between the two tanks sometimes goes out of wack. If the gages are simply stuck, the problem should resolve it self. But if the gages are bad, only option is to replace them at $$$.

[SLPRC5]

Originally Posted by hamstar

This problem sometimes happens with C5. I had the similar problem with my C5 several times. With split gas tank, the gages that monitor the gas level between the two tanks sometimes goes out of wack. If the gages are simply stuck, the problem should resolve it self. But if the gages are bad, only option is to replace them at $$$.

If you leave the C5 sit too long on below 1/2 tank the sending unit on the passenger side drys out causing a resude on the contacts to form scale on them from gasoline with too much sulfer in it...Cheron and Union 76 won't cause this problem..
Techron will usually cure the problem...not sure about the C6.

[RichieRichZ06]

It is possible the sender is bad, but even according to GM, it can be caused by "dirty" sender contacts. We always try a bottle of the GM additive. It is very similar to techron and available at any dealer. There is also a reflash of the newest update to the PCM for the fuel issue. Here is the TSB on the issue.

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#PIC4765A: Erratic Fuel Gauge Operation DTCs P2066 And/Or P2636 - keywords cluster empty gage inaccurate inoperative instrument IPC needle panel dender tank - (Feb 21, 2008)

Subject: Erratic Fuel Gauge Operation DTCs P2066 and/or P2636


Models: 2007-2008 Chevrolet Corvette




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This PI was superseded to update the information that step 5 is always performed. Please discard PIC4765.


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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
Some customers may comment that the Fuel gauge goes to empty when the fuel level is greater than what is shown on the gauge and DTCs P2066 and P2636 are present. When these codes are present the Fuel Level Low message should be displayed on the DIC. This could be caused if the ECM does not receive the expected voltage signal to indicate that the fuel transfer is properly occurring. If this condition exists for 30 minutes both of these DTCs will be set. The fuel level sensor card may have slight discoloration possibly caused by fuel contamination which can affect the level sensor output. The fuel level sensor diagnostics are sensitive to this issue.

Recommendation/Instructions:

Verify that P2066 and P2636 DTC are set.
Confirm fuel rail pressure with the fuel pump on is 58-62 psi. If the pressure is not within this range, follow eSI Service Procedures to correct the issue and then proceed to Step 5.
Confirm proper jet pump transfer by checking and recording the fuel level sensor voltages using a Tech2. This must be performed with less than 3/4 tank of fuel. If required, remove sufficient fuel from the Schrader valve on the fuel rail. Follow all safety procedures as outlined in SI. Clear the DTCs to get a reading on the fuel gage. If the secondary (passenger side) sender is less than 2.2 volts and the primary (driver side) is more than .86 volts, the secondary (passenger side) level sensor and the module (includes the jet pump) should be replaced. Prior to replacing fuel hardware confirm all wiring connections are fully seated and harnesses are properly routed. After replacing the level sensor and module move to step 5.
If the jet transfer pump is operating properly the fuel sender card may be contaminated. This could cause an incorrect voltage signal to be sent to the ECM. Customers should be advised to correct a contamination issue by adding one bottle of GM Fuel System Treatment PLUS (part number 88861011) to the fuel system on their next fuel fill. Note; the fuel level must be below ¼ tank when the fuel treatment is added. The treatment rate is 1 oz. per gallon of fuel (Using one 20 oz bottle to the fuel system is acceptable). To clean a severely contaminated fuel level sensor, it is permissible to treat the fuel system on two consecutive tanks.
Note: Back to back treatment is only permitted once in the life of the vehicle. After the initial treatment, customers should be advised to add one bottle of GM Fuel System Treatment PLUS to the fuel tank at every oil change, however, not more frequently than once every 3000 miles. Proceed to step 5

A revised ECM calibration 12624797 is available through TIS2WEB under the fuel system heading. To reflash the ECM please use labor operation L1199

If the vehicle continues to have the concern after the calibration has been updated it is possible there is an intermittent jet transfer or an intermittent stuck float arm issue. Poor jet transfer could be due to an intermittent clog in the jet pump or a kinked transfer line in the either fuel tank.

Fuel contamination is discussed in service publication 05-00-89-078B and Top Tier Fuel is discussed in publication 05-06-04-022D. These documents should be provided to customers if they have questions regarding fuel quality. E85 fuel requirements are reviewed in publications 06-06-04-035A and 05-06-04-035C. E85 must not be used in Corvettes.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

[avbump]

Thanks everyone for all the information. I took the vehicle to the dealership on Tuesday. Four days after the light came on & gauge read empty, despite having a full tank.
They have experience this before, put car up on hoist & recalibrated the fuel card (flashing) & said drive it. IF the light comes on again, drive it until I have 1/4 of a tank of fuel. They will add a fuel system additive & see if that helps. If not, they will replace the fuel sending card. Also requested I run 93 octane fuel.....WHERE can I get that? We only have 91 octane gasoline in our area! BTW Chevron was $4.85 today for premium. OUCH

[norman19]

Originally Posted by shalenss

I think it has something to do Bush and Chenney J/k
I'm no help bro but never happenned to me, if it happens,You might wanna post on C6 forum

it is caused by dirty contacts in fuel tank senser,use a bottle of tectron with next fillup

[mickey_7106]

Originally Posted by hamstar

This problem sometimes happens with C5. I had the similar problem with my C5 several times. With split gas tank, the gages that monitor the gas level between the two tanks sometimes goes out of wack. If the gages are simply stuck, the problem should resolve it self. But if the gages are bad, only option is to replace them at $$$.

i get it all the time i dont even bother looking at the gauge. everytime i fill up i reset the trip mileage and measure from there

[napacruzerc5]

Originally Posted by norman19

it is caused by dirty contacts in fuel tank senser,use a bottle of tectron with next fillup

Techron Fuel System Cleaner (similar looking bottle of Techron Fuel Injector Cleaner) works better although I use the Injector cleaner annually.

[andy82]

Originally Posted by 99C5Alan

A lot of intermittent fuel gage problems have been caused by gas with a high sulfur content. A year or two ago half the mid-west had problems when a large quantity of gas was produced. Some people claim one brand of gas or another is better quality and some people buy Chevron's techron additive and use it to prevent such problems.

My C5 has occasionally shown low gas when it should not have but always corrected itself shortly.

I had the same issue with my C5, started using Chevron and the issue went away.