Re: Electric fuel pump for evinrude 235
IF running to the water then pump would only activate the 1/2 lb pressure switch after the thermostats open, unless you are running the pressure from the tell-tale, then the switch might work.
Use the output from the rectifier before it goes to the regulator for your positive VDC, negative side of the 12vdc relay will run to a switch on the console so you have positive control of the fuel pump, you can disconnect the fuel pump as an emergency cutoff by opening the circuit at the switch, disconnecting the ground so the relay is not energized and no positive VDC to the fuel pump.
This configuration gives two safety features, fuel pump on only when engine running, (output of rectifier),and safety cutoff switch controlled by the operator so fuel can be cut off at any time engine is running.
I do like the idea of using the pressure sensing switch, guaranteed no over heating problems. No water flow, no fuel.
This will keep unnecessary wires from underneath the cowl, not a whole lot of room under there anyway.
You got my interest up on this project, please keep informed of the results. Enjoy and be safe,WAV