fuel gauge

[plowking35]

Does anyone know why the fuel gauges on 03 and 04 trucks seem to be having problems. I have an 04 LLY that after a fill up on friday, the fuel gauge now reads empty, with the low fuel light on. I went to the dealer today, and they cleared the gauage, and got it read properly, I had 3/8 of a tank, so I topped off, and the gauge read fine for about 10 minutes, then dropped to empty with low fuel light on again. The truck was shut off for fueling, on level ground. It was not idled for long periods off camber either, I have a friend with an 03 that had the same issue. Only he went 10K before it happened, and he had the gauge cleared, and it has been fine since. Both trucks are cab and chassis with 2 tanks.
Dino

[More Power]

I suspect you have a dual tank issue. The ECM reads the senders from both tanks, and automatically transfers fuel from the auxiliary to the main tank when a prescribed % of fuel is needed to maintain the main tank level.

Without a lot of dual tank trucks out there (and more reports appearing here about them), it's hard to know whether there might be a bug in the software, wiring or fuel pump relay system, or if your particular truck has a faulty component.

MP

[plowking35]

Thanks MP
The truck will go in next week or so. In the mean time I just wath the trip meter, and fuel up every 250 miles just to be safe.
Dino

[Bellrule]

Mine did the same thing in December. Didn't have time to get it in just then, so I just watched the odometer. About two weeks later it started working again. Then in February it quit working again so I started watching the odometer. Well after what should have been have a fill(25 gal) the truck stalled and was out of fuel. Turns out that this time it quit pumping from the back tank to the front tank as well. Took it in and they fixed things but the wife picked it up so I'm not sure what they did to it. Anyway it has worked fine since.

[plowking35]

Mine doesnt seem to be pumping from the rear tank. I filled up today, and only the rear tank took fuel the front was full. It goes in Tuesday, we will see what happens.
Dino

[dmaxmule]

I did not know that these trucks had dual tanks. That is a new one for me. Are all of them this way? I have never seen that option listed.

[Bellrule]

The cab and chassis models have dual tanks.

[plowking35]

The gauge operates again, but I suspect that it isnt acurate. The truck also still seems to not be using fuel from the front tank. The dealership printed out a bulletin from the GM tech help line, it was a total load of double talk. Basically refers to the if the truck is idled for a long period with the gear selector in Park, and on an 8% or greater incline or grade, it will trip a false empty reading on the fuel gauge to kill the fuel transfer pump, to keep cavitation from occuring. Only good news is that it occurs with both gas and diesel engines.
I have never idled the truck on a grade, and the 2 times the gauge tripped was imediatley after a fill up.
Any ideas?
Dino

[More Power]

Is there a sequence listed in the owner's manual for filling one or both tanks? Based on what you mentioned, there appears to be a safeguard in place to prevent the transfer pump from doing something unexpected, like transfer fuel when it really shouldn't.

MP

[plowking35]

So today my friend with the 03 cab and chassis, who is an electrician, stops by the job site to do some work. We are laughing and cracking on GM about this lousy fuel gauage issue, and when we are done, he restarts his truck to leave, and guess what, fuel gauage has stopped working. We are going to lobby GM for 2 pieces of wooden dowel, so we can stick our tanks.
Manual states to fill front tank first. However, mine is always full, I can add but 1/2 a gallon before it spills over.
Dino

[plowking35]

When I dropped my daughter off to school today, I let the truck idle for approx. 15 sec, to let her out and the guage tripped to empty. I called the dealer and then GM to start a case number.
$ 35000.00 and they cant get the fuel guage to operate. What a joke! Can you imagine GM having to buy the truck back for this.
Dino

[plowking35]

Since Friday I have spoken with several cab and chassis owners, both gas and diesel powered, and GM has a big problem and can not figure it out. Every owner I have spoken too, has had this issue from day one. The code gets reset and the problem reappears in less than 1000 mi. I now have a file case number with GM, and we will see what happens. MY front tank wont take fuel, it stays topped off, so I can only run on the rear tank. Sucks having to fuel up every 200 iles, up side is that it doenst cost as much to fill up.
Iwould sure hate to see GM buy this truck back, because they cant get a fuel gauge to work. How silly would that be.
Dino