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Erratic Fuel Gauge

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Old Nov 23, 2018 | 02:51 PM
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Default Erratic Fuel Gauge

Hi all, I've been poking around the forums learning about the "Fuel Gauge/Check Gauges Light" issues many have experienced, I also found an excellent video on uT'b documenting the painstaking repair on a C6 but nothing of substance for the C5. Apparently the greatest difficulty is in removing the cross over tube because of some plastic lock ring?, and then there are the esoteric EVAP connectors which are not very visible making them difficult and frustrating to disconnect.

My C5 '04 M6 is probably a candidate for this repair as the gas gauge intermittently drops to empty and then Check Gauges light displays, it will drop to read Empty after every fill-up yet oddly enough the gauge will read correctly once the tank is below 1/2 and just above 1/3 full ... not sure why this is but I'm guessing my problem may be with the passenger side tanks unit.

Appreciate your thoughts and any advice that may help me. And yes, I have put through 2 bottles of Techron so far and plan to do a couple more ... looking for an ez way out LOL.
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Old Nov 23, 2018 | 03:33 PM
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I'd say that the Techron approach is the easy way out. I'd run several more through. Two may not be enough.

Last edited by billschroeder5842; Nov 23, 2018 at 03:35 PM.
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Old Nov 23, 2018 | 03:45 PM
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Thank you for your reply, that's the plan for now ... with a little luck I'll reply to this thread grinning ear to ear
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Old Nov 23, 2018 | 04:06 PM
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Moved to C5 Tech.
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Old Nov 23, 2018 | 04:31 PM
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I’ve had this problem. Starting using chevron gas and it was fixed.
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Old Nov 23, 2018 | 05:45 PM
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Techron is magic. Fixed my gauge problem after adding a 20 ounce bottle in two miles. I've been using it every dix months for five years because it works.
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Old Nov 24, 2018 | 07:01 AM
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Is it better to add Techron to an EMPTY tank and let the car sit for several days or add Techron then FILL up the tank and let the car sit. Which is more effective?
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Old Nov 24, 2018 | 07:05 AM
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Chevron gas is great, unfortunately I haven't seen a Chevron station in North Jersey for a very long time. Not sure which gas stations
other than BP (which contains Invigorate, whatever that is) include something to help breakdown the sulfur deposits.
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Old Nov 26, 2018 | 12:22 AM
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I added the Techron to a low gauge reading and then filled up. Letting it sit IMHO would not be as good as driving and letting the gas move around.
I tried Techron on my 2001 and it did not fix the problem. I ended up pulling the units out of the tank and cleaning them with a soft brush using lacquer thinner and had a re flash done on the PCM that was in a tech bulletin. I have not had any more problems in three + years. I know your car is not as easy as mine and I hope the Techron works for you.
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Old Nov 26, 2018 | 12:51 PM
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I stopped at Walmart and p/u a couple 10oz containers of Techron, I emptied one into the tank and will fill-up with premium as I'm 1/3 full now.
Hoping to see some improvement soon.

If anyone has tried anything other than Techron I'd like to hear how that worked out for you, perhaps there's something stronger than techron.
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