JR-01

I was cruising this morning with a little over a quarter tank of gas and all of a sudden the gas gauge went to zero and low fuel warning came on. I went to a gas station filled it up with 12 gallons and the gauge worked again. I know these cars have two tanks but do they have two sending units too? Did the first tank go empty causing the warning light to come on?
I hope this isn't a new ongoing problem. I did put a bottle of Techron in it hoping that will fix the problem. Any comments?

runner140*

Techron is a fix....sometimes takes a couple bottles. The sending unit gets sulfured up.

JR-01

I hope you are right. Do you think that was the problem this time? It worked when I filled it up. Is that how they act when they get sulfered up?

Chicago1

Why band aid? get a new sending unit and replace it. it's easy and yes there are 2 if I recall. I pulled the driver side and it's just a siphon pump and I believe a sender. Also drain the tank by triggering the relay it's less messy then what I did the first time.

new sending unit..



going in ....



Bastard went in finally . took me wayyyyyy longer then it should of but didn't wanna break anything again..Here it's hooked up to the casper harness. looks factory huh?





Cover removed..



Making it rain....



To much rain....





For future reference make sure you have 1/8th tank of gas.. Like it's been said a ton of times..



Coming out..



That a boy..



She's out

strand rider

I have had that problem , and still do, only after a steady and uninterrupted fuel drain run.

In my research, I think it is caused by the eductor(transfer) jet being worn/out of spec, and no longer transfers fuel at the correct rate between the tanks.
The computer then sees the fuel level between the tanks as outside of it's understanding, and defaults to low fuel.
Techron is not an answer for this problem.

I freely admit this supposition of mine could easily be incorrect, save for the techron advice. All top tier gas includes this type of additive, so unless you are filling at some bootleg gas station , you are already running it with every fill up.

I have also read that there is a factory recall available to reset the computer fuel understandings and that the fix is effective. I haven't checked this out personally.

JR-01

Does that cause the gauge to bottom out too or just get the low fuel warning? My gauge went all the way to the bottom. Then when I filled up it went back to normal. I have only been making short runs the last few weeks.

JR-01

It's not really a band aid if it fixes the problem.

mike_engr

I'll probably get flamed (again) for commenting on this because I've only had a C5 for a few months, but here's my understanding: The reason for a Gage sudden drop to zero is because computer senses that the gas level sensors (two tanks) dis-agree by too much of a margin! The computer drops the gage to zero as a fail-safe to insure the driver fuels up promptly and gets it checked regardless.

TECHRON seems to have solved my one-time "event" for now - - plus I am watching my gas gage more carefully and using my trip odo to make sure I get gas before exceeding my typical range. I think its worth a try since its a lot less invasive than removing/replacing the sending units. As the weeks & months go on, I'm using Techron and gaining confidence in my fuel system again!

JR-01

If the warning comes on at quarter tank, I can live with it as long as the gauge goes back to normal after a fill up. Sometimes I think they over engineered these cars and made them way more complicated than the needed to be.

Chicago1

When you add it every month so it doesn't appear or add it more then once then yes it is. I tell people get your hands dirty and fix it and not limp it along until next time. It doesn't fix the problem because it always comes back after sometime. hell if that was the case I want my wasted money back that I spent after the first bottle because I got robeed. lol

JR-01

Eventually your new sensor will have the same problem. It's a design flaw. Your band aid just costs a lot more than the Techron. I have worked on cars for 40 years. At this point I like driving them more than wrenching on them. If a bottle of Techron fixes the problem I will be happy.

torchredmadness

I have never had any luck with the Techron fix. My low fuel / check gauges warning comes on after every refill. With in the first five miles it's back to normal until next fill up. Most of the gas put in the car is from Chevron.

Choreo

I had both my sensors changed under extended warranty. New set made it about 2 years before the same issues. I use Techron at least every 2 fill-ups and when that quits working, I add a can of BG-44K and that gets it going again for awhile (so long as the jet-pump stays unclogged).