Re: Fuel pump relay Trigger??
It seems to me that you could skip wiring up the starter selenoid for now. Just use your primer pump before starting to fill up the carb float chamber. That will be enough to get your engine running until your pump turns on.
If the purple accessory wire stays hot when the engine stalls and the key is still on, it is not safe as a hook-up for an electric fuel pump. The idea of using the alternator sounds good. Is there a place on the alternator that gives you a steady 12dcv that goes to 0 volts when the engine stops and the key is on? I don't know, but I would like to know. Wouldn't the alternator just give varible AC voltage? Hooking into the system just after the alternator would likely supply 12dcv, but is likely to stay hot from the battery when the engine stalls. I wonder if there is a place on the power pack that would provide a suitable hook-up? Anybody know?
(Here's another safety consideration: Electric fuel pumps are fuel pushers, not pullers. Therefore, electric pump manufacturers recomend that the pump be placed close to the fuel tank. The problem with this in a boat installation is that it puts a long length of pressurized gas line under the deck. When gas leaks occur, there will be a rapid accumulation of gas out of sight in the bilge. So in a boat, safety comes first. The pump hose to the engine should be short have few or no connections between it and the carbs intake manifold. It should be mounted after the primer bulb, so that the bulb can be used to prime the electric pump. It seems to me that mounting the pump inside the engine cowel would be the best bet as long as spark-free waterproof electrical connections are used.)