C6ToGo

I have the dreaded "Service Fuel System" with the corroded passenger tank sender. Now it is throwing code when both full AND when 1/2 empty. So there is a problem on both ends of the sensor contact.

I assume the sender sends a certain ohm resistance to the control module as it travels during the fuel level drop.

My question is...is there a way to disable the wires to the right tank sender and add a resistor at the proper ohm reading that will trick the car into thinking the right tank is always empty.

I would hope that would stop the DIC messages and DTCs. My thinking is the gage would always read no more than half full due to the wire change and then would drop as the left tank is emptied.

I would rather have the gage reading be wrong at the half-full or greater level and be accurate when fuel is low and not have all the dings.

Thoughts?

HOXXOH

The problem is almost always the fuel. Try adding a bottle of Techron to every tank until the DIC message goes away. Then either add a bottle about every 3rd tank or switch to Chevron gas that includes a dose of Techron.

My first problem of that sort came at 8K miles. I switched to Chevron and I'm at 114K now without a repeat issue.

ls1121

So this is caused by Cheap gas?

Gearhead Jim

Usually, it's the cheaper brands. But not always.

A good rule of thumb is to buy from companies on the Top Tier list, not a guarantee but tilts the odds in your favor.

~Stingray

What is wrong with cheap gas that throws this error?

carpe dm

Marvel Mystery Oil used to work for the same problem in the C5.

Gearhead Jim

My understanding is that something in the fuel tends to coat the contacts for the sensor, causing the erroneous readings.

A few years ago, people were saying the problem was sulfur in the gas, not sure if that can still be an issue.

As mentioned, higher priced or Top Tier don't guarantee success, but they help.

Our recent Corvettes have been 2001 (66k miles), 2006 (44k miles), and now 2009 (currently 63k miles). I always use Top Tier gas, and use a bottle of GM Fuel System Treatment + (probably re-labeled Techron) every 15-20k miles and have not had any fuel gauge problems.

VET4LES

I agree but because I only drive about 3000 miles a year I add the additive about once or twice a year. I've never had the problem.
Check out this link for the top tier companies. http://www.toptiergas.com/retailers.html

Bandit's C4

On my 93; before the sending unit was fixed properly... monitored my trip odometer, refilling at 300 miles. Now refill every 200 miles regardless on either the C4 or C6 - not allowing the sending unit get too low.

Buck-I

Techron is the key. Fill up and put a bottle of this stuff in.

Then just run solely Chevron gas, as they add Techron too it. Keeps the sensors clean, or so I have been told.

My C5 had the same issues, and this is how I solved it. If I was out of town and had to use other gas, I had to add a bottle of Techron about every 3-4 tanks.

Cheaper and easier than replacing the sending units.

FortMorganAl

No, there is not a resistor. That is the way they worked 50 years ago. Today we have computers to make our life more complicated. As you know, there is a sending unit in each tank. The BCM compares readings on both senders and sets codes for a multitude of possible failures. If both senders aren't correctly measuring their associated tank levels you are going to have problems. If you were to fool the BCM into thinking the right tank was half full then as the left tank dropped while the right didn't change it would think the transfer pump had failed. Maybe set the right tank as empty all the time ...

A far simpler fix is to just try cleaning the sensors with Techron. Yes, cheap gas is a problem in these cars. Cheap gas doesn't have the additives needed to keep the engine and fuel system clean. That's why car makers created the Top Tier association. GM was spending too much on waranty repairs from cheap gas and it was more economical for them to work with other makers and develop minimum additive requirements for gasoline and then tell you in the owner's manual to not buy cheap gas.

BTW, buying cheap gas and then adding Techron too often is also a problem. Better to just get the right additives with every fill-up than to go without and then overdose.

C6ToGo

The reason I was asking is because i have done all the Techron, Regane, Seafoam, Marvel Mystery Oil treatments. I don't want to overdo them as that is probably not good either.

When I fill up, I get the message for 30 miles. Then at half tank it comes on again. Kinda sucks that I only get peace from 7/8 tank to 1/2 tank. What is that...about a hundred miles??

Makes sense that there are multiple computer checks.

GuyFromLeMans

Yup. Have the same issue. Maybe the third most common vette problem after the harmonic balancer and the auto shifter stuck in park.....
I've been throwing the techron on fill ups, not fixed yet, it comes and goes so I'm gonna keep the techron hoping it will eventually fix, but in the meantime I reset my trip meter when I fill up, so when it gets close to 250 miles, this tells me it's time to fill up in case the gauge is acting up.

FortMorganAl

Here's an idea from 50's tube radio technology: Since your issue is the high and low limit on one sensor, maybe rubbing the sensor at those points could dislodge the corrosion. Fill the tank and, as soon as the gauge starts working, top it off so the sensor goes back to the bad spot. Do this a few times and if that solves the high end issue, repeat when the right tank gets empty adding maybe a gallon to get the gauge working again and scrub down to where it doesn't work. Just a thought. Probably won't work but that is the way you get a noisy volume control working on an old radio with a wire wound pot. It might work to remove the deposits.

ben dover

Give this a shot, I'd like to know if it works.

erikszr1

also refrain from filling the tank 100%. when you do that the sending unit goes to the end of the scale. it doesn't like to be there, it looses contact. try it

GMJim

From your owners manual in the fuel section.

Some gasolines that are
not reformulated for low emissions
can contain an octane-enhancing
additive called
methylcyclopentadienyl manganese
tricarbonyl (MMT); ask the attendant
where you buy gasoline whether the
fuel contains MMT. We recommend
against the use of such gasolines.
Fuels containing MMT can reduce
spark plug life and affect emission
control system performance. The
malfunction indicator lamp might
turn on. If this occurs, return to your
dealer for service.

MMT was causing HUGE problems with fuel senders in Canada and the northern US. Canada tried to ban it but decided to monitor it's use. Some US companies (based on what I've read) still use it.

http://www.autos.ca/environment/auto...ive-continues/

Just stick with TOP TIER fuels.

C6ToGo

That's an idea. I only add Techron after I make sure the tank reads half full. So when I finished filling, I am hoping that the highest concentration of Techron would be sent to the right tank.

robot doctor

other cars don't have the same issues, do they.
I replaced the senders in my 07, both of them. they are junk. take a damaged one apart, the brass/copper feathers that travel across the windings break of,f no other reason POSSIBLE. since the sender is basically a rheostat "dimmer switch" just another case of who makes it cheapest.
just my learned opinion. AFTER dissection. problem started at 30 K and always used chevron, still do. I have their card

ALS 08

I did 2 bottles of Techron, double dosage. On the third day problem cleared up, All good ever since & have been using Techron only 1 or 2x per year since.