I have a '46 Ford Super Deluxe with the six cylinder engine and 6 volt positive grounded system. I am installing an in-line fuel pump to use for priming after periods of non-use or vapor lock situations. I found a small Bosch relay to use. My question is, since I am using a positive grounded system, should I reverse the toggle switch circuit leads so that the "grounded" marked pole goes to the toggle switch and the "switch" marked pole goes to the ground? I know that I do this with the fuel pump and I noticed that the relay includes a diode so polarity is important. The "power" side shouldn't make any difference.
As long as the diode is "reverse biased" the relAy will work. If the diode is in the wrong way, it will act as a dead short, and let the smoke out= dead
A switch to turn the relay on can be in the non-grounded lead. The relay is what matters, just make sure that if negative ground, the relay minus goes to ground, positive ground, then the relay + terminal goes to ground. If you are worried, put a fuse in line with the relay.
If it really is to be a primer or vapor lock solver only and not run continuously, why not just run a fused negative wire to the switch, other side of switch to power wire on pump. Just make sure to use a little larger wire since it is 6 volt.
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