Fuel Gage issue on TV

[Shorty Cox]

My tow vehicle (’07 Classic Chevy 2500 Duramax) has a 26-gal tank. My argument with myself regarding an in bed auxiliary tank has always been, “I need to stop and stretch my legs every couple hour.” However, on my last long trip, I changed my mind. I purchased and installed a gravity flow in bed tank and just returned from its maiden voyage. Now for my problem and question.

Obviously, the in-bed tank is going to keep the main tank full until the in-bed tank is empty. Here is my problem. After traveling several miles (approx. 80 miles) I hear an alarm, look down the fuel gage is showing empty. When I stop turn the key off, then back on, gage immediately goes back to full. Once again, after traveling additional miles, I hear the alarm, look down, gage shows empty. Turn the key off then back on, gage shows full.

Any thoughts? Anyone else ever experienced this issue? If so, what is the solution?

[RoadrunnerII]

Bil has a newer 2018 Chev same issue.
His solution is run a couple hours then open aux tank.
On our Ford f250 never an issue

RoadrunnerII

[Shokyle1]

I put a larger tank in my in-laws chevy. It went in place of the stock tank. Around 80-100 miles the gauge stops working for about 20 or so miles then it starts working again. I contacted the dealer they say they have no way of changing the tank size in the ecm. I believe the drop out is the computer thinking the gauge stopped working due to no change in the level for too long.

[sturgissteele]

Guess if were me, go by mileage with plenty of buffer. But if you want peace of mind, just stop in a rest area, quick stretch/walk/bathroom break and be on your way. Upon cycling the key, you'll be all set until the next alarm. Does it happen quite quickly, like within minutes?

[Shorty Cox]

Sturgissteele, It does not happen quickly, it take several miles. I was hoping someone has had the same issue and could shed some light.

A friend told me that most likely because the fuel tank is remaining "full" for a long period of time, the ECM senses that the fuel sending unit is not function properly and shuts off power to it. Hence, when the key is turned off then back on, it resets the fuel sending unit. Sounds logical to me. On my next outing, I'm going to close the in bed tank valve an only travel on the main tank and see what happens.

[sturgissteele]

Originally Posted by Shorty Cox

Sturgissteele, It does not happen quickly, it take several miles. I was hoping someone has had the same issue and could shed some light.

A friend told me that most likely because the fuel tank is remaining "full" for a long period of time, the ECM senses that the fuel sending unit is not function properly and shuts off power to it. Hence, when the key is turned off then back on, it resets the fuel sending unit. Sounds logical to me. On my next outing, I'm going to close the in bed tank valve an only travel on the main tank and see what happens.

Yeah, that does make good sense.

Good test. Maybe it'll be better to wait until you actually need the aux. tank and then valve it on, that way the ECM will just "think" you filled up and everything is normal. To me that would be better than what you're currently experiencing. Good luck with all; hope it works out to your satisfaction.