Originally Posted by Thor_449
An easy test would be to see how much vaccuum your engine has. Generally you want around 17 in Hg. They sell vaccuum gauges at most auto parts stores for cheap. Also if it's having problems with the gas tank being at 1/2 I would have dropped the tank first before moving on. Just my two cents though, they put screen socks on some fuel pumps when they instal them. if this screen is plugged on the bottom but not the top, that could also do it. Meaning when the truck is above half full it's sucking through the top of the screen. Also is your fuel gauge accurate? GM's are notorious for their fuel guage sending unit to go bad or become off, maybe you have less fuel then you think.
fuel gauge still works properly as far as normal conditions the only differnce I have notice with the gauge is when I am at a 1/4 of a tank and the truck stalls out at a stop light and I start it back up it will then show 1/2 a tank until I drive about 20 feet then it goes back down to a 1/4 of a tank like it was.
I will pull the tank off first then I was unaware of the being something over the pickup line can you purchase these seperatly.
I know it is going to be a week or so before I can touch it tank is full right now and have to wait till a check clears to fix this problem.
I'll let you know what I find out on the sock I will also do a vac test once I learn how to lol not something I have ever done