The color of gasoline

"Tighten gas cap" means

1. That there is an air in-leak somewhere in the vapor recovery system of the car. Hoses and hose connections is a suspect place. So is the electric carbon canister vent valve. OR
2. It also can mean out of spec gasoline from the discount gas station.

If this was my car I would:

1. Top up with some decent gasoline.
2. Have the local shop clear the code and see if it comes back. Maybe do this several times until I am sure all the suspect gasoline is gone.
3. If it does, and as a last (expensive) resort, have the shop or dealer "smoke test" the emission system for leaks.

Good luck.

How long has it been since this car has been fired up? If its been a while then change out fuel. Smell it, it may have been messed with. I have never seen green gas.

Which brand? What kind of gasoline? Some cars doesn't run with all gasoline grades also there is some gas station with poor quality of gasoline.
Happened to my car too, I always use SHELL but one day I stop in the MOBIIL gas station to put some gas, got home and the next day the car won't start had to by the STP aditive to put in the gas tank. wait about 10 minutes and car starts fine.
Another thing is my car won't run good with all gasoline grades
I always use the regular one.

Fuel Pump

Check for it working,pressure at motor,
pumps age, run out of fuel ruins them

are you talking about the color of the gas cans or the color of the gas?

Typically green gas cans are designated for Diesel fuel. Diesel should never be used in a vehicle that requires unleaded gasoline.

A blue container is usually designated for water. If these containers are used to store fuel for small engines than there is a possibility that the fuel is mixed with 2 cycle oil. This "mixed" fuel should also not be used in any automobile.

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I'll bet it misfires because of the old gasoline. Since it was sitting for that long, you should remove the old gasoline from the car and put in fresh gasoline. You might want to put in a can of seafoam in the gas tank as well to clean up anything the old gasoline could have left behind.

Next time, if you're planning to have your car sit for a few weeks or more, put fuel stabilizer (such as Seafoam) into the gas tank before you leave. That way, you can safely start it when you come back.

Usually its fine to use regular unleaded gasoline in most cars anymore, but to be safe i would look in your owners manual and see what the manufacturer specifies, most cars now have whats called a knock sensor on the engine with regular gas the knock sensor detects engine knock from lower octane gases and tells the computer how to adjust ignition timing until engine knock disappears, being all cars have a knock sensor on them it usually is safe to use regular gas unless a turbo or supercharger is being used on the engine this application usually requires a higher octane gas to run the engine smoothly but as for your appilcation there should be no reason you cannot use regular gasoline, the computer will adjust your ignition timing as need to maintain good engine performance through the knock sensor.

well first of all, it's a good thing you're draining it, because there's rust in your gas tank. Second, you're going to have to siphon the gas out, and third, use a proper technique, because i doubt that gas is too tasty

Cheers

Chris