Ok, I have a 2004 silverado crew cab z71 and it runs out of gas sometimes when it says I have an 1/8 of a tank and today when I had just below a 1/4. It never seems to be the same. Every once in a while the yellow light will come on but usually I don't make it to that point before it runs out. Does anyone have any ideas to why it isn't consistent?

 

Sounds like a sending unit issue. A lot of people don't realize that consistantly running below a quarter tank plays hell on the pump since it uses the fuel bath to keep it cool. Personally, I'd wait and do both at the same time since it's the same procedure.