toilet
I know there are several posts on toilet fill valves and supply lines, but I'm afraid that my issue may be much worse.
My toilet was draining slowly so I got a professional grade auger and ran it into the toilet. The toilet still drains slowly, but now when it tries to refill the bowl, it won't stay filled but completely drains out.
I don't see any visible leaks on the sides of the toilet. What could be going on?
It seems as if you have an obstruction that may be floating around in the pipe or valve. Sometimes it obstructs sometimes it flows clear. I would start with changing the water valve. If this is the old style "gate" valve there are several things that can clog the line. I would replace it with a 1/4 turn ball valve. That will give you much better flow than a gate valve. You will need to shut down the water probably at the main. The old valve is probably soldered, but you could cut it off and use a compression type valve instead. "Sharkbite" is one such supplier. Although I have never used their compression valve, I have used their end caps and found them to work well.
If you can have someone hold a bucket under the pipe once you cut off the valve and then a second person turns on the water main to fill the bucket to purge the line of any debris. With cast iron pipes it is common to get clogs from rust build up. The rust may not pass the small opening in the old gate valve when you first purged the line.. Although you did not mention what type of pipes you have, if it's copper than you won't normally find rust obstructions..
That's a fairly popular fill valve. To open it:
The cap will then lift off and you can inspect and clean any parts. Before reinstalling the cap, move any small parts to a safe location, get a small cup to place over the top of the valve, and turn on the water supply. This will jet water straight up from the top of the valve and clear out any debris.
Reinstalling the cap is the reverse of the above procedure. Put the parts back, position the cap back on top, lift the float, press down on the cap, and twist.
Note that if cleaning it doesn't work, it's fairly simple to replace this fill valve.
Best Answer
Nothing has changed, your toilet still drains too slowly, you still need to clear the obstruction. The bowl completely clearing will sometimes happen with partially obstructed toilets because, due to the very restricted passage, the vent air that normally breaks the siphon action cannot make its way to the bowl until long after all the tank water has been completely drained into the bowl, leaving no fresh water to refill the bowl.
As soon as the passage is cleared to its normal size, the vent air will have room to work towards the bowl and quickly break the siphon. The bowl is then refilled with the remaining fresh water, ready for another flush cycle.
ADDENDUM
Depending on the nature of the obstruction, if it's difficult to completely clear with an auger, and assuming the toilet bolts are not too badly corroded, it's worth removing the toilet and working at the obstruction from both ends. It's usually easier than most people think. There is still a portion of the passage that is difficult to reach, but you've doubled your chances. For the typical floor mounted residential toilet you will at least need a fresh wax ring to reinstall the toilet.