It depends on the type of the plastic, however it is safer to replace the tank, instead repairing it.
Buy a new or used tank.
No it is not illegal to have a plastic gas tank
There is no safe way to repair a plastic fuel tank, you must replace it.
how much to fix a gas tank on a 93 grand cherokee?
How do you fix an airlock in a 2002 ford explorer gas tank.
There are emergence repair kits but I would suggest replacing ot for safety sake.
You can stop a leaking gas tank, by making a paste of soap on the hole of the gas tank.
take it to the fix place...................................................................................................................................................................................................................................................................
To fix a gas tank seal leak you must drain the gas into an empty bucket and remove the tank. Then, cover the outlet holes with putty and re-install it.
What kind of plastic gas tank. -If on a road-going vehicle, beware of insurance issues with repairing a gas tank ( to say nothing of possible fire due to gas leakage)
I have used krazy glue, super glue and epoxy on various kinds of plastic gas tanks. In my opinion epoxy does the best job and seems totally impervious to gas. -However if this concerns a road going vehicle please consider that there may be safety or insurance issues in repairs to gas tanks. If I encountered a crack on a gas tank in one of my road vehicles, I would find another good tank rather than repairing one.
The fuel sensor is in the gas tank and probably needs replaced, the tank will have to come out to fix it.