I was on the road yesterday and checked the fuel guage and it was one mark past the half and thought that was more then enough to get us to where we were going and back. It was a little over 100 miles round trip.

On the way in as we approached our destination the check guages lite came on and the fuel guage was reading below empty. I had just put on a new fuel filter and thought that gas might be running out all over under the car or something so I took the next exit and got down and everything underneith was fine, no gas anywhere. My wife says I looked at the wrong guage but I know where the fuel guage is.

Took the first exit and filled it up and it took 10 gals.
I am thinking the auxillary tank is not pumping into the main tank to refill it and so I am running on 9 or 10 gallons in the left side tank. Or the guage is just whacked.

After filling it the guage did not do anything for a second or two then swung over and now showes full and seems to be working fine.......

Tom, you got any ideas? You are the resident C5 go to guy.

Yup, it's a common problem. Let me guess, you use CO-OP gas? Most gasolines, although they come from mostly the same refineries, have lots of sulfur in them. This sulfur builds on the connectors in the gas tank causing this very condition.

I would suggest dropping in a couple bottles of Techron for the next several tanks. The Techron is Chevron's cleaner and detergents that they put in their fuels. That's the big difference between the Top Tier fuels and the others.

I also will use Saefoam, drop a bottle in the tank and let it sit. It will eat the corrosion off the connectors. It's a recurring problem.

Thanks Tom, I have some seafoam I will give that a try.....I love Co-op fuel....I get a discount.....

It's not on the Top Tier list of fuels, because it doesn't have the detergents and cleaners in it. Big problem around here is there aren't that many Top Tier dealers. I usually just dump in a can of Techron every other tank or so. And if the problem rears it's ugly head I'll drop in a can of Seafoam and let it sit for a while.

I've heard those pumps are pretty expensive. I really hope the cleaner fixes it.

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I have heard some horror stories....like 1500 bucks for parts and labor.......the C4 had it way over the C5 in that department. I have not seen a lot of fuel pump failures show up on line though. I think they are fairly reliable. TB would know more......

I did inquire at Racetronx about a pump set up from them and was told that at only 85K miles not to worry about it. They should know.....

Like was mentioned it is a common problem and a search can be your friend. Good luck Marcus. May the system cleaning gods be with you.

Mine acted up the day I bought it, driving home from Albuquerque. Once I got home I put Seafoam in it and let it sit for a week. It has done it once since then. I just Seafoamed it again. When I'm on the road I try my best to use a Top Tier gas....Shell, Phillips 66/Conoco, Chevron. If I can't then I put in a bottle of Techron.

Marcus, another friend told me to use Gumout Fuel Injection Cleaner. He says it works great, and is much cheaper than Seafoam or Techron plus.

Ok thanks Tom....

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Yous guys puttin" Gumout in them cornputerized new cars? I knows a few sekerts about that there STP stuff.

A quick tech issue with the C5/C6 and I assume, C7, fuel tanks.

There are actually TWO tanks. One behind each seat. One tank has a transfer pump, the other a conventional fuel pump. The transfer pump moves fuel from one tank to the other and keeps them level during operation.

This process is more than a little bit temperamental. Consumer Reports indicates that the fuel delivery has a black spot for reliability off and on since 1997.

Then take into consideration the inherent lack of reliability the fuel delivery has had over the years...