My car died and is not worth fixing. I decided to junk it.
Unfortunately it has a full tank of gas. I can't siphon it out due to check valve.
Is there a way I can engage car's fuel pump and have it pump gas through the fuel rail and a hose into a gas can?

WARNING

Make sure you ground the container(s) to the car to avoid a spark and fire.

Gas falling through the air can produce enough static electricity to cause a spark'

I have seen a repair garage have a serious fire caused when they drained the gas from a pickup truck into a open container. (38 years as a firefighter)

There may be a valve, like a tire valve on the fuel rail for testing. You might be able to put a fitting on that to pump the fuel out without a big hassle.

If not, look for some other type of plug or fitting.

I think that there is some way to test fuel pressure on the fuel rail.

Try asking a better target for your question iike "Is there some easy way to drain a full fuel tank on an S70?"

The title space for a question is a lot longer than one would think.

Do not start some scheme to drain the gas that you cannot stop - 18 gallons is a LOT of gas.

There must be a way to connect a hose to the nipple on the fuel rail and then engage the fuel relay and have the fuel pump do its job.

What happened that you decided to junk the car?

Way too many issues and serious problems. It's like losing a family member...but, such is life.