Fuel sending unit failing?

[OL Yeller]

During a drive last weekend, I was about 30 minutes into it, when i heard a chime and looked at the dash..My fuel gauge was reading dead empty with the fuel light on. I know there had to be at least 20L in the tank because i got fuel a couple weeks before and didn't go anywhere. It was reading just below half full before I left home. I pulled intp the station 2 km later and filled up. The light went out and the gauge showed full.

I am wondering if it is the beginning of the sending unit going to crap out.

Has anyone replaced a sending unit on one of these cars? I am hearing that it is quite the job. If this does end up being the case, should I replace the 2 fuel pumps while i am in there? Anything else to replace at the same time?

Any advice will be appreciated.

Thanks in advance.

 

[Murray20c8]

That happened to me with my C8! Only once, but it was really curious.
Is yours an LS1 with a plastic fuel tank? Ethanol can wreak havoc with fuel senders I'd imagine.

 

[Black 03 Z06]

Wondering if it could be something as simple as crap building up on the sender after its long winter nap? I forget the additive that seems to help with this, don't think you can buy it in Canada. Mind has gone blank, not surprising. Someone on here will know. Popular stuff.

Good luck with it Don.

TECHRON. Thats it!!!

 

[OL Yeller]

That happened to me with my C8! Only once, but it was really curious.
Is yours an LS1 with a plastic fuel tank? Ethanol can wreak havoc with fuel senders I'd imagine.

Yes, LS1, plastic tank

 

[OL Yeller]

Wondering if it could be something as simple as crap building up on the sender after its long winter nap? I forget the additive that seems to help with this, don't think you can buy it in Canada. Mind has gone blank, not surprising. Someone on here will know. Popular stuff.

Good luck with it Don.

TECHRON. Thats it!!!

I am hoping that's what it is...I store it over winter with less than 1\4 tank...even think last fall the fuel light came on on just before I got home from my last run. So whats this techron? octane boost, Injector cleaner?

 

[Black 03 Z06]

Don as far as I know it is a cleaner. Maybe someone knows a Canadian source for it, no idea why it cannot be purchased here. I knew someone who had a few bottles of it a while ago, will try to check with him about availability now. The method of use is to let the fuel gauge get down to about a quarter tank then add the Techron, that will fill both tanks with the chemical.

 

[Kanuck]

Techron can be purchased from Amazon.

 

[Black 03 Z06]

Another thought on low fuel level in the tanks. Realize sometimes you just cannot avoid getting low on fuel but it is my understanding that the fuel in the tanks actually cools the pump motors. So if the fuel level is really low it can cause issues with the pumps getting hot. Not good!

 

[OL Yeller]

If the weather cooperates on the weekend, I will take the car out for another run just to see if the issue comes back...I will try and find some of the techron to add to the fuel system..Thanks

 

[OL Yeller]

Update:

Took the car out for a spin on Sunday...about 200 km...the fuel gage worked as per normal. I did, however, order the TECHRON from walmart.ca and it will be delivered to my local store within 2 weeks.

 

[OL Yeller]

Update #2:

I received my 20 oz bottle of Techron in less than a week and the instructions say to add it to an almost empty tank and fill it up.
I have to burn half a tank of fuel out of it before I can dump it in and see what happens. Will report back after that.

As a footnote, this was shipped via Purolator from Ontario. I have no idea if this company sells retail but if you guys in Ontario are looking for Techron, You might want to give them a call to find out. You might be able to drop by their place and pick it up.
IBS Automative
35 Riviera Drive Unit 13
Markham, ON
905-604-1929

 

[Murray20c8]

Update #2:

I received my 20 oz bottle of Techron in less than a week and the instructions say to add it to an almost empty tank and fill it up.
I have to burn half a tank of fuel out of it before I can dump it in and see what happens. Will report back after that.

As a footnote, this was shipped via Purolator from Ontario. I have no idea if this company sells retail but if you guys in Ontario are looking for Techron, You might want to give them a call to find out. You might be able to drop by their place and pick it up.
IBS Automative
35 Riviera Drive Unit 13
Markham, ON
905-604-1929

I just watched a video comparing Techron, Seafoam and Marvel mystery oil. All three were about the same.

 

[OL Yeller]

Update 3: Was out for a run on Sunday and just as the fuel gauge got to 1/3 of a tank, the gauge went to E again. Drove to the local Shell Station, dumped in the Techron and 50 Litres of Premium (so there was still 20L left in the tank). Drove the 1 km home and the light didn't go out. Checked the DIC and had code P1431. Cleared the codes and the gauge went back up to full.
Did a bit of research on the Interwebs and found out that after a while the sending unit connections corrode and it loses connection...up to 2003 you do not have to drop the gas tank (and everything else behind the doors) to fix the issue. Just remove or burn off the fuel in the tank, take off rear tire, a sheild and there's the pump. From what I can gather, it should take around an hour and a half to replace. Sounds like a job I am willing to take on if need be. If the Techron doesn't do the trick, I will replace the fuel pump and the sending unit while i am in there...no sense doing the job twice because you know that will give out after as well.

Stay tuned...

 

[Black 03 Z06]

Good luck Don. Thanks for keeping us up to date.

Under current law you will have to calculate the amount of fuel you drain out and then pay taxes on the amount of fuel you put back in. New or used they don't care!

 

[Hal]

During a drive last weekend, I was about 30 minutes into it, when i heard a chime and looked at the dash..My fuel gauge was reading dead empty with the fuel light on. I know there had to be at least 20L in the tank because i got fuel a couple weeks before and didn't go anywhere. It was reading just below half full before I left home. I pulled intp the station 2 km later and filled up. The light went out and the gauge showed full.

I am wondering if it is the beginning of the sending unit going to crap out.

Has anyone replaced a sending unit on one of these cars? I am hearing that it is quite the job. If this does end up being the case, should I replace the 2 fuel pumps while i am in there? Anything else to replace at the same time?

Any advice will be appreciated.

Thanks in advance.

I had same problem with my C5. Ethanol gums up one of the sending units. I put a can of a product called Seafoam in the tank and fill the tank as per normal. Use this every couple of fill ups and the problem should go away. By the way if you fill the tank now you will see the problem disappear. It’s when the gas starts being delivered from the second tank that the problem shows up. Good luck.

 

[OL Yeller]

Which tank is the primary tank? I think its the driver's side one. I wouldn't think that both tanks have sending units, just the primary one. There would be only a pump in the passenger side tank to push the fuel into the driver's side tank. If the Techron doesn't work, i'm going to replace the pump and sending unit in the left side tank. Have to do something, can't be driving around all summer waiting for the fuel gage to go to empty, without burning the full tank of fuel.

 

[Hal]

Which tank is the primary tank? I think its the driver's side one. I wouldn't think that both tanks have sending units, just the primary one. There would be only a pump in the passenger side tank to push the fuel into the driver's side tank. If the Techron doesn't work, i'm going to replace the pump and sending unit in the left side tank. Have to do something, can't be driving around all summer waiting for the fuel gage to go to empty, without burning the full tank of fuel.

My understanding is that there is a sensor in both tanks and the computer does some fancy math to know if one is reading below a certain voltage and the other is above then it is an estimation of the actual level. I’ve been using the Seafoam for about 2 years and only experienced the problem a few times. I then learned of a software upgrade that is available that dealt with the accuracy of the fuel gauge. I had that done last summer and have not seen the problem since.

 

[OL Yeller]

My understanding is that there is a sensor in both tanks and the computer does some fancy math to know if one is reading below a certain voltage and the other is above then it is an estimation of the actual level. I’ve been using the Seafoam for about 2 years and only experienced the problem a few times. I then learned of a software upgrade that is available that dealt with the accuracy of the fuel gauge. I had that done last summer and have not seen the problem since.

Where did you have the software update done? Dealer? Do you have a number for the update?
Good idea to put a couple of bottles of fuel system cleaner in the tank every year as well...I think I will start doing that.

 

[Hal]

Where did you have the software update done? Dealer? Do you have a number for the update?
Good idea to put a couple of bottles of fuel system cleaner in the tank every year as well...I think I will start doing that.

I have a mechanic that used to work for a GM dealer and he advised me of the software upgrade. I don’t have the upgrade info at the moment but will try and get some info and reply to you.

 

[reghenderson@hot]

Update 3: Was out for a run on Sunday and just as the fuel gauge got to 1/3 of a tank, the gauge went to E again. Drove to the local Shell Station, dumped in the Techron and 50 Litres of Premium (so there was still 20L left in the tank). Drove the 1 km home and the light didn't go out. Checked the DIC and had code P1431. Cleared the codes and the gauge went back up to full.
Did a bit of research on the Interwebs and found out that after a while the sending unit connections corrode and it loses connection...up to 2003 you do not have to drop the gas tank (and everything else behind the doors) to fix the issue. Just remove or burn off the fuel in the tank, take off rear tire, a sheild and there's the pump. From what I can gather, it should take around an hour and a half to replace. Sounds like a job I am willing to take on if need be. If the Techron doesn't do the trick, I will replace the fuel pump and the sending unit while i am in there...no sense doing the job twice because you know that will give out after as well.

Stay tuned...

am having some issues with mine not starting on the first crak usually hits right up on the sceond once in a great while it takes 3 but very rarely, i had a tech tell me fuel pump but the i thought it has 47k miles and the gas filter has never been replaced and lo and behold guess where the puel pressure regulator is? yeah in the damn gas filter might explain the $128.00 dollar price $300 retail at the shop i am gonn change this before i drop $1300.00 dollars on a pump change!