Breather tube as a return line

If you put the canister back in, then it will still need to be purged... which means putting the vapor control lines and controls back in the engine compartment. I have been trying to figure up a bad scene of fuel spillage with this being used as a return, but have not thought of one yet. I'd push some low pressure air back into this line with the cap off, and see if it comes out the filler; there were some funky purge line configurations and you want to see if there is a check valve anywhere, and if it will flow adequately. Then use a vented cap as RRR suggested.