From my BN2 Heater manual:
- Fuel Pump Orientation:
"This is a “Pusher” pump. It is gravity fed and needs to be lower than the fuel tank feeding it. The pump also requires that it be mounted such that a line drawn through the inlet and outlet is angled up on the outlet side by +30 degrees above horizontal. This is needed to prevent the pump from getting air bubbles in the outlet side during operation. "
Mine works at 30 degrees. The angle is NOT especially precise, so don't sweat it too much. I got a big, rubber insulated cable clamp (Home Depot or Amazon and the rubber surrounds the pump circumference) sized so that it firmly holds the pump and have it holding the pump at the right angle. If your pump is longer, you could use two clamps attaching the pump to a bracket of some sort.
Power source: As Dave mentioned, find a source (fuse panel?) which is switched on with turning the key on and run a separate (red) wire from there over to your new pump. Make sure you attach to the fused side of the fuse, not the feed side. Use insulated or waterproof connectors on the pump end because of the wheel splash from the incessant rains in the Panhandle. NAPA can help with those. An alternative is to use hooded connectors and shoot some silicon caulk onto them to seal them after pushing them onto the pump tabs.
Don't forget to run a Green or Brown wire from the pump to ground. No ground source out on the passenger chassis tray? Just drill a convenient 1/4" hole through the tray, scrape off the paint or undercoat around the hole to about 1/2" dia., top and bottom.
Install a 1/4" bolt from the bottom with the following stack-up: Bolt head side should have a 1/4" star washer between the bolt head and the tray metal, coming up from the bottom, then a 1/4" star washer on top, then a 1/4" nut, tightened. Then another 1/4" star washer on top of the nut, then the 1/4" ring connector with the green or brown wire, then another 1/4" star lockwasher, then a 1/4" nut, tightened. Once tight, goop up everything with silicon caulk both on the nut side and on the bolt head side to seal it - be liberal. Any silicon caulk will do, but Home Depot sells the stuff in black - Jus' sayin'......