Originally Posted by redynvre
What would you recommend for a rear electrical fuel pump? It seems it will requiere a 15lbs pressure capacity from what I understand.
Thank you for the help!
I would recommend the Carter # P4070, or similar. It's 72 GPH @ 4-6 psi. A carbureted engine only needs 2-3 pounds at constant loads. Even a Holey Red or Blue pump would be fine though. The Holley Blue pump is a very common pump on an RV, and delivers 110 GPH @ 15psi. It's capable of pushing fuel the entire length of the coach. Holley has been having some quality control issues lately though, so it's not my first choice right now. The maximum working pressure for any carb would be 7lbs, after that the pressure holds the needle and seat open and floods the carb. It's a good idea to keep the fuel pump pressure at or near the maximum though because under a heavy sustained load, the 2-3 pounds can drop to zero.
Most RV's that have an electric fuel pump usually maintain a mechanical pump mounted to the engine. This precludes the need to run a regulator, and is the reason you need to run a rotary vane style pump, which is pretty much all you'll find on RVs. The mechanical pump (which can pull the fuel from the tank) 'is' the regulator for the system. The electric pump, which can push fuel, but is lousy at pulling it, is used to keep the mechanical pump supplied. The mechanical pump will not allow over 6 psi to go passed it. The rotary vane style pumps are not only internally bypassing, allowing the extra pressure to bleed off, but can allow (some) fuel to pass through the vanes, drawn by the mechanical pump, even if the electric pump isn't working.
I hope this helps,