Insure your pump well if you choose to ship it USPS. I've had 2 packages (priority mail) disappear in the last year.
I've flown with strange auto parts and tools. They got pissy once because my tubing bender was 6.75" inches long, and the maximum length for metal carry-on items is 7". They let me bring it on after 3 minutes of explaining what the Roswell-alien-looking-probe really does.
As for checking your bag, you shouldn't have any problem putting an ip in there. I once checked a pizza oven in a plastic box. I just opened it up, showed the woman at ticketing, and she stuck the sticker on, and away it went on the conveyer. A pizza oven is basically a huge toaster. It has weird electrical wires on it with a literal timer on the side. If anything looks like a bomb, it was that, and no one detained me.
Just open up the top, fuel screw port, and easily let all the fuel drain out for a whole day. Then wrap it in CLEAR plastic, so TSA can easily see what it is. Maybe print the moose IP instructions and conveniently insert them along side the IP, so they get the gist. They WILL inspect the device, so giving them information in your checked bag will make it easier for them to move it along faster.
