Each spring I take a two-week 5000 mile ride (+/-) on my 2000 C10.  I usually leave the petcock in the reserve position and go by the gauge-I have adjusted the arm on the sending unit so I would be switching to reserve just as the needle hits the red zone.  On two occasions, admittedly a couple years apart, the bike has died with the tank half full.  I was unable to switch the petcock from reserve to on while riding, so I coasted to the side of the road with a dead engine. 
After moving the petcock lever to the on position and cranking the engine a few seconds, it started and ran great the rest of the trip.  I did, however, fill the tank before hitting reserve.  I have now run the gas down and drained it as much as possible, and I've removed the sending unit and petcock.  I see the screen completely around the tubes on the petcock and find it hard to understand how there could be enough crud inside the tank to plug it up.  I emptied the last of the gas from the tank over an oil drain pan and could see just a few flecks of copper colored material in the gas.
I am wondering if anyone else has encountered this or has any ideas or suggestions on something else to check.  The first time it died I considered it just a random event, but the second time has got me looking for something I could condemn, but so far I haven't found anything.  TIA

Larry  aka  CharlieDog
Bristol, TN 

I've had problems similar to yours. In my case, if there was a good breeze to stiff wind coming from the right(think South Dakota winds) , my bike would starve for fuel long before hitting reserve. What I did that alleviated the situation was to move the gas tank overflow hose to a different spot, basically let it hang loose. My theory is that the side wind hit the hose when stuffed in that holder creating a vacuum. This drove me nuts for over a year, until I relocated said hose. Never an issue since.

YMMV

What you should have done was drained the float bowls into a glass container, or the tank into a can, and looked to see just how much water had actually condensed in the tank.... it would be clear. Running on reserve allows a couple more gallons of fuel theat has water in it, to be drained into the carbs. One or two drops of water will totally shut you down.

Just to note...
Its springtime again, and for the last 10 years, I am answering the same question... not to say you would know this, just saying that storage gas is crap, condensation takes place, remove and completly drain a tank before expecting to ride trouble free is the answer before the problem ever arrises...

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Wanna make this a sticky?

Another possibility might be a clogged tank vent in the gas cap. Check by opening.

Another possibility might be a clogged tank vent in the gas cap. Check by opening.

had the same issue, it was this  . Steve

On my bike I had replaced the vacuum line which operates the petcock with a line that was very flexible/pliable.

I had run it like that for years.

A few years ago I was heading west to Colorado, into a stiff wind of around 25mph, cruising about 80 indicated.  Strapped onto my seat was a big tent setting sideways (not the most aerodynamic) and I had the bags on and full too.  Outside temp was in the 90's.

Passing a semi the bike just dies like it was running out of fuel so I slowed down, got back into the right lane, and then headed to the shoulder.

After a few minutes of troubleshooting, I turned the petcock to prime and saw fuel start to flow.  Away I go.   I turned the petcock to on a few times once I got going and the bike would die each time until I switched to prime.  I rode in the mtns the next few days on prime.

Coming home the temps were cooler and I wasn't fighting a headwind and it was slightly downhill.  I thought I'd try the petcock again and it worked fine, as it proceeded to do over the next few months.

I figure that pliable vacuum line was probably getting too pliable with all the heat  and was collapsing on itself, shutting off the fuel flow.  I replaced the line with more rigid line and its been fine ever since.

Thanks for all the ideas / suggestions.  Just what I was hoping to get.