fuel levels....
 

so, i have an older truck, a GMC R3500 to be exact.
i noticed when i got it that i was low on gas....well, after attempting to fill it up, the gas only read at half full.
i decided to keep a gas can on me and run it dry doing errands and what not to see where the empty level was, assuming it was really full and the gauge was off. last night it died while i was parking at the house(the fuel gauge on E), i didnt think much of it and just went to bed, this morning while trying to start it, not thinking of the fuel(because i thought the gauge would go below E when it was really empty)
turns out it was empty, so i said "ok, lets put some in it at the house, then go fill it up."
after attempting to fill it at the gas station, i check the level, it was a little under half...
im not sure if this would have to do with the pump shut off, or the fuel bobber to tell me the level, or what. all i know is it wont go to full, i need to find out why.

Chevys have problems with the gauges all the time. My 05 has problems with it, as does my dad's 98, my brothers 98, and my moms 94. I always just hit the trip meter,a nd then fill it when it gets to about 200 miles or so. Mine isnt as bad at the res tof them. My brothers is about a half a tank off, on the full side. My moms sticks at 1/3 and won't go lower, and my dads truck just bounces all over the place. My truck just goes all the way up till about the last 1/8 of a tank. All have the same problem, the sending unit for the gauge, and it cost like 200 bucks to fix, and you have to pull the tank out. My truck seems to have quit doing it after changing the fuel pump though.

What year is your truck? single tank or dual ?

I believe he said it was a 89 in one of his other post.

sorry, last night i was talking and typing, yes, it is an 89.

im more curious on why i cant fill it all the way than the gauge, i figured the gauge would be bad because its old.

The tank isn't filling all of the way, or is it just not showing on the gauge? With some of the older trucks, you have to stand there and hold the fuel pump and don't set it for auto flow. Just hold it and let it pump as slow as it will go. The older fuel pumps were not as fast as todays, and the anti theft device won't let the fuel through fast enough, so it builds up pressure in the tube, and shuts the pump off. It is a pain in the next, but most of the trucks that I have had that are older then about 1992 have been that way. You just have to let the gas pump as slow as it will go.

i ran it empty the other day, as said above, then when i went to fill it, it only took 16 gallons.

Ok, try just trickling the gas in after the pump shuts off. You may also have to pull the nozzle out of the tube most of the way. The older trucks do that because the pumps were not as fast back then as they are now.

It's difficult to diagnose a vehicles fault unless you can physically see the fault.

I've seen some people take their vehicle back to the dealer for your very same issue. Turns out. The user (customer) had to change their filling up style of gassing up their vehicle. Their new car can't take the fuel from the nozzle at full trigger. The tank needs to VENT while fuel enters. If it doesn't vent fast enough? It will trip the trigger on the nozzle.

When your 16 gallons are done. Can you squeeze more until it over flows?

it didnt over flow,