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Fuel Gauge Stop Working

nfhjr

Charter Member
SM 2003
Full Member
Joined
Feb 6, 2002
Messages
1,948
Location
Philadelphia Pennsylvania
Was out yesterday and the LOW FUEL showed on the dash, knew i had atleast half tank ANYONE have this happen too them and how is it fixed :eek: :eek: :E: :E: :help: :help:
 
The fuel pump assembly comes with a float switch and the sensor itself which I believe is just a resistance measurement.  If you have easy access to the fuel pump (via the floor cut hole mod), you could pull it and check it out or swap with a new one.  Because you got the "LOW FUEL" alarm, its probably not the gauge in the cluster.  That makes it extremely likely its the sensor in the pump or wires leading to it. 

I would disconnect the battery for 15 mins and reconnect before doing anything just to see if a module reset could help.

 
Add some fuel system cleaner that unstuck mine a couple of times.
 
MS03 2500 said:
Add some fuel system cleaner that unstuck mine a couple of times.
cleans junk of resister used to measure fuel tank...

problemmany years ago when I think Texaco add some funky stuff to fuel..
 
I believe it was sulfur in what they called winter blend gasoline.

I haven't had the problem  since I retired. I don't drive it as much, but a bottle of techron system cleaner cured it
 
I suspect it is the stepper motor for the fuel gauge going bad.  Low fuel light is usually pretty accurate since it is a very simple thing to turn on a light.  What you describe is a pretty common problem with Avalanches, Silverados, and Blazers.

In this system, the PCM reads the resistance of the fuel sender in the tank and sends a digital signal to the instrument cluster on a single data bus (a wire) that all the signals for all the gauges are on.  The instrument cluster has a processor that interprets this data signal and drives stepper motors for the gauges to where they are supposed to be.  Other gauges working correctly indicates the PCM and processor in instrument cluster processor is working in general for the gauges.  Typically a stepper motor goes bad.  Ain't it wonderful!!  If you think so, just study the electronics it takes to put your avalanche in 4WD with the push of a button.

What you want to do is read what the PCM says the fuel level is, using a capable scan tool.  Car Gauge Pro for your Android phone and the BAFX Bluetooth OBD2 adapter (as sold on Amazon) will read the fuel level the PCM is seeing for about $30 total.  Your gauge should match.  If it doesn't and other gauges work fine, blame the stepper motor.  If the PCM reading matches the gauge, and you know you have a certain fuel level - then suspect the fuel sender.  Ebay has replacement stepper motors if you are tech savvy and handy with small fine work.  Otherwise, replace the entire instrument cluster ($$$$$$) if a stepper motor is bad.

Good luck and best wishes for a successful repair.
 
I could be wrong, but I doubt it is the gauge.  Reason is, I'm pretty sure the low fuel light warning comes on by using a comparator circuit (this is separate from the gauge).  So if this is pegging as well, that must mean the resistance measurement itself is indicating low.  The sensor could be dirty, or the float switch itself could be mechanically stuck.
You could try some fuel cleaner-- you might get lucky if its just gunked up...  although when I replaced my fuel pump at 120k there was no gunk whatsoever to be found and I always use the cheapest gas I can buy...
 
Have tried adding fuel cleaner twice,(did raise fuel milage) filled gas tank and disconnected the battery for 10 min. still gauge not working so will lower tank level and take to the dealer.
 
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