The car started for 2 seconds, then I couldn't start it again. I'm going to take the trolley to get a 4th gallon at the nearest gas station.
There is also an Advanced auto part store close by the station. What would I need to buy to blow out the fuel lines?

 

I forgot that was the code which started this. Are there any others?

It isn't very likely that you actually have water in the tank. Don't fixate on that, it is probably not your car's issue. Still, you could probably have a shop drain the tank for you for not too much. It probably isn't the issue, but on the other hand, it would get the acetone out, and it may be the least expensive first step. While you could siphon it out yourself what are you going to do with what comes out?


Honestly, there are a lot of ways a car can slowly fail so that the cat gets messed up. Unbalanced injectors, failing oxygen sensors, bad rings in one cylinder, iffy spark plug, and on and on. Anything that results in excess unburned fuel. Some of these might throw additional codes. A failed catalytic converter will give you that code but it wouldn't normally keep the car from running unless the exhaust was seriously blocked. It would fail a smog test, not fail to run. Have a helper try to start the car (even if it is just turning over) is there exhaust/air coming out of the exhaust pipe? If yes then the converter is not completely blocked.

It may be time for a visit to a mechanic...

 

The code that started this was P0420, there was no other. No air coming out of the exhaust pipe.
With the 4th gallon, the situation improved, the car went forward for 1 meter, then stopped. I should have not tried to go forward. I'm going to get a 5th gallon (I take the trolley, I don't have a bike) and try again. If the tank is full and I don't fix it, I will have to tow it tomorrow and bring it to the mechanic I guess.

 

Just to be sure we are all on the same page: the motor was turning over for at least several seconds and there was no air/exhaust coming out the exhaust? Even if the motor wasn't firing at all it would still act like an air pump and some air should have been coming out. It sounds like the exhaust is blocked somewhere, and completely. That would fit your "it runs for a short time and stops" description.

Stop everything you are doing and take it to a shop.

 

Sorry, I was confused, I thought about smoke coming out. I didn't see if there was air coming out because I was behind the wheel. Right now, the car doesn't start even for 1 second and the gas tank is almost full.
To put the gas, I used a 1 gallon empty bottle of water. There were a few drops of water in the empty bottle, is that a big deal?

 

Maybe my biggest mistake was that I should have drove somewhere far until the tank is empty. I didn't know I had to do that in 1 or 2 days. Instead, my problem happened after several days while the tank was half full. I will have to tow the car.

 

Keith wrote "top it off and drive it until nearly empty". I didn't know I had to do that the same day.

 

Stop messing about and take it to a mechanic.

A few drops of water on the bottom of the tank is the least of your worries. There are commercial products that you can add to the tank to remove them later, once the car is working again. A random plastic bottle should not be used to store gas, as the gas can melt through it, or make it so fragile that it breaks, or it can extract plasticizers and other gunk from the plastic and who knows what those will do to the car. HDPE/LDPE and PET, which are what most plastic water bottles are made of, stand up to gasoline fairly well. That means the bottle probably will not fail as a container, it doesn't mean that they didn't contaminate the gasoline to some extent. Car supply stores sell gas cans for not much, $12? In future it would be best to use one if you need to transport gas.

 

Thursday night, I added Road assistance to my Geico insurance (only $9.33 for 6 months). On Friday morning, I used road assistance for a jump start, because we tried so many times to start up the car that we thought the battery was dead. The guy tried to jump start it but it didn't work. He then started to tow the car, he put it started in neutral. Half way on the ramp, the car suddenly started! He tried driving it around the block and it drove fine. I cleared the P0420 error code on Torque. I drove 90 miles yesterday. The car drove fine and the P0420 error didn't come back. You can also look at this screenshot on Torque: https://photos.app.goo.gl/9xGBQpkuOvGjaAVl2
Maybe the 1 gallon acetone method is good for bigger gas tanks than mine. In summary, the car stopped after half gas stank. Then I used once a rented bike, and several free trolleys to go to the nearest gas stations to put 6 more gallons of gas so the tank is full. Probably half a gallon of acetone is better than 1 gallon.

 

He left the key in the ON position and the car in neutral? A car wouldn't normally start from that condition if it wasn't running - you should be able to push it all day without the motor starting. What the heck could have started the motor?

1. It dropped into gear briefly for a "push start",
2. Something fired up the electric motor and that started it.
3. The starter motor kicked in (maybe the switch was not quite to ON and slipped over to start?) Seems very unlikely as it takes force to move it to the start position. Also you didn't report hearing the starter motor.
4. There was a gas/oxygen mix in one of the cylinders under compression and the ignition set it off. Also really unlikely, it takes careful engineering to set up a car motor so that it can sit like that and still ignite the cylinder. That's how Mazda does autostart on some of its cars.
5. Gremlins

At this point the last one seems just about as likely as the others! If the battery was really down to nothing the car's logic might have lost its mind enough for 1 or 2 to be possible, sort of an electrical/logic glitch where it wasn't sure what gear it should be in, or thought it was in autostop, and then thought it should come out of it.

Now, why did the car stop running in the first place? Fuel system blockage maybe? Interesting that the car started when it was tilted, presumably nose up.

Anyway, glad that it is running again.