I recently got my primary tank working again(which took some troubleshooting) But, now i have another issue im wondering about. So, my dual tank system is now operational, but even when both tanks are about on E they collectively wont hold more than 35 dollars which is about 12 gallons between the 2 or 6 gallons a tank, which obviously cant be right. Has anyone had a similar issue or a possible explanation?

 

We get these types of posts now and then. People think the fuel level system in these trucks is super accurate, it is not. 1st thing, all vehicles leave at least 2-3 gallons in the tank when they read empty. Its a reserve that just naturally happens, the fuel pickup that you just installed does not rest on the bottom of the tank, its above the bottom of the tank a couple of inches. That along with the size of the tank leaves a few gallons that you will never get out. An then I don't know if you noticed, when the float hangs down on its lower stop, its above the pickup. So there is another gallon or so.

You will also find these fuel level units are not consistent. On my truck I drive now, the rear tank was fairly consistent, but the front tank after filling to the top will hang above the full mark on the gauge for a long time. Then once it starts moving off the full mark it moves fast. In other words 1/2 tank is probably at 3/4 on the gauge. It's just the nature of the beast. It's the way your particular truck is, and you get used to it. As long as you don't run out of fuel, that is the main thing.

If you want a more accurate way to monitor your fuel, you can do it easily if you have trip odometer in the speedometer that you can reset. Fill the tank and while you are at the station set the trip odometer to zero. Then drive like you normally do, and go to the station like you normally do when the gauge is on empty. Fill the tank again, note the mileage on the trip odometer and then reset it. Note the amount of fuel you pumped in. Most of these trucks have a 19 gallon tank unless you have a shorter bed. If you only put in 12 gallons, do the same routine again but run the mileage out a little further. Most trucks that do not have a 460 can get around 12-15mpg. This time see how many gallons it takes, and you can keep bumping the mileage up till you get a comfortable number. You will find this is a much more accurate way to know how much fuel is in the tank if you drive the same routine everyday. I will warn you though, I would not push it too far. If you have 19 gallon tanks, and are putting in 16 gallons, I would say that is the limit.

 

^^^THIS^^^

Our trucks also have a poor vent in the fuel tanks. This causes the fuel pump to quickly click OFF when filling the tank (especially when using the lock function on the fuel pump). If you don't have that problem then apparently the vents are in good condition on your truck.

 

My truck has dual tanks. When either tank hits E, it still has six or seven gallons in it. Been that way since it was new.

Still running original pumps and sending units.

 

I'll add my truck will drop from full to a little below 1/2 a tank quickly, then begin to move slower, until it gets about 3/4 empty and then begin to move even slower to empty.

Years ago I would carry a container of gas with me until the truck ran out, then I knew how low the gauge would go. Problem is now, that was so long ago, I've forgotten how low it will go...LOL