If the can doesn't explode, which I would bet on it doing, what will happen when you open to see that nothing happened?
If the tracer passes through liquid gasoline, nothing happens, as there is no oxygen present.
If the tracer passes through gasoline vapor above the liqiud in the tank,
probably nothing will happen, as the oxygen content is likely too low. YMMV for various reasons.
If you open the can after the tracer passes through to see what is happening inside, again nothing will happen*, because the source of ignition is long gone.
* Except you might get a little gas leaking out of the can onto your shoes. Watch out for those vapors if you are smoking.
Mythbusters had fun with this one already.
ETA: Gasoline vapor - Lower Explosive Limit = 1.2%, Upper Explosive Limit = 7.1%. That is a pretty narrow range.