hamster37

'06 Vette coupe, 90k miles.

A little while back the fuel gauge suddenly dropped to zero and the car popped up "service fuel system" in the info display.

The car still runs fine and fuel efficiency seems normal (managed 400 miles on one tank since it glitched), and it displays correct instant/average fuel efficiency, so apparently the problem is just with the way it sees the amount of fuel left in the tank.

Googling this problem gives me a number of suggestions, ranging from reflashing the onboard computer to replacing the fuel level sensor or some related electronic parts. One suggestion was to put some Techron in the tank and to try to clean the sensor that way. I did one bottle of Techron, with no luck.

If I disconnect and reconnect the battery, fuel gauge initially goes to 1/2 (when the tank is really full) then after a while drops to zero again. Last time it took 4 miles after the reconnect for it to drop to zero.

Called one local Vette mechanic, he said that the fuel level sensor needs to be replaced, which is at least a 2-day job that involves removing the transmission and costs somewhere on the order of $1000. (He did not actually look at the car, this was all over the phone.)

Am I really out $1000, is there an easier way to deal with this, and, if it's fuel sensor / electronics related problem, can it be worked around without taking half the car apart?

How does this system work anyway? I have the basic schematics, but not the full service manual. I see in the schematics that I have a "sending unit" ($290), "harness" ($70) and "level sensor" ($50), two copies of each, one per tank. I'm guessing that they all connect together and plug into a port in the top of the tank? Which one is most likely to have failed, and can I get to them from the cabin side?

tennblkc6

let the tank get to a tad bit lower than 1/2 tank and add a bottle of techron a couple of times to sees if it helps. normally it's the pass side tank fuel level sensor that goes bad first.

TXredc3

I agree. Will be an easier job if you have a manual tranny. Lots of labor.

KB9GKC

Hello,

Too late to run Techron, that needed to be done regularly before the sensor failed.

My thought is that the ethanol is the culprit and here's why. If you let fuel with ethanol sit for any length of time it will attract some water. The water and ethanol mix chemistry becomes acidic and attacks the variable resistor on the fuel level sensor causing it to corrode and turn green. The green material is not conductive and the circuit is broken and your fuel gauge becomes inoperative.

Here's a youtube video of the complete job of fuel sender replacement.


Douglas in Green Bay

87SAM

I do not necessarily believe that it is too late for Techron. The same thing happened in my C5 and Techron brought it back.

sick cc

Try techron but I installed a low mile take out set of pumps in mine and has the return line in front of the level sensor in the the drivers side and realized this after I put the drivetrain back in and the gauge didn't work and also had service fuel system but I plugged my old pump into the harness and moved the float and worked. I ended up dropping tank with the drivetrain in the car and reinstalled the pump with the hardliners out of the way of the float arm.

ZHZ-416ci

Sorry but I have a question related to fuel line and tank
I can smell a gas inside the car if it's parked for 2-3 days, I checked if there is any leake or smth but every thing is ok!
Any idea about this issue?

hamster37

I went through 2 tanks and 2 bottles of techron, with no apparent effect. I'll probably end up trying to get into the tanks as demonstrated by the video, though I don't feel very optimistic.

torquetube

The passenger one probably failed but you should pull the code(s) to confirm. It will tell you.

If you've got a manual gearbox, it does not need to go anywhere in order to drop the tanks.

Nothing is accessible from the cabin. The tanks have to come down.

Model year 2006 has the old-style level sender that increases in resistance with fuel level. In later years it was the other way around. Be sure to get the right part.

After changing the sender and reassembling the tank, test the resistance with the tank right side up and again upside-down. This will confirm that the float is able to sweep through its full range. People skip this step only to discover a problem once the tanks are back in the car and full of fuel.