Put your tailgate down. Then stand the pump in the upright position about two feet from your tailgate. Tip the pump and lean it against the tailgate, so it’s at about a 45° angle or so. Then lift it up at the base and slide it in (may take two people if it’s not gutted).
Tips: You can bring some dowel rods and use them as rollers if you want to push it in easier. You can also put a folded blanket on the corner of your tailgate when you lean it over and lift it in. It’s a little less stress on the door/sheet metal. Bring a dolly with you. And final tip... if the ground is uneven, put your rear tires in a low spot so the tailgate is lower to the ground.
Push it to the front and then strap it from the base to your front anchors with good straps.
I actually use a wood frame with a notch with rollers, since I move a lot of pumps. Tom Buckles shows the design in use here......http://www.oldgas.com/forum/ubbthreads.php?ubb=showflat&Main=108737&Number=652242#Post652242