Redundant oil pressure safety switches?

[skhorleb]

I just purchased the MMI engine-mounted electric fuel pump kit. My original mechanical fuel pump repeatedly leaked. The kit includes a new oil pressure safety switch (with 2 terminals.)

I previously had installed the Cole-Hersee Marine engine warning alarm kit which also included an oil pressure safety switch (with 1 terminal.) I see no good reason to have 2 oil pressure safety switches. I would like to keep things simple, swap out the old one (which is plumbed-in just ahead of the oil pressure sensor behind the flywheel), and use only the new one in it's place. Also, this approach would preclude the need to remove the oil plug located just above the oil pressure adjusting valve.

As for the wiring, I was planning to simply connect 1,) the wire from the fuel pump plus 2.) the wire to the Cole-Hersee alarm module (part # 4099) to one of the terminals on the new oil pressure safety switch...Then connect the (+) wire from the coil to the other terminal on the new safety switch.

All of this stuff is 12 volt. Anyone see any compatibility, safety or functionality problems with this approach?

Thanks.

[Don Moyer]

While the switches in the Cole-Hersee kits and switches in the fuel pump oil safety kits are both normally open switches, the Cole-Hersee switch closes below a certain pressure to sound an alarm while the fuel pump safety switch closes on raising oil pressure to complete the circuit to the fuel pump. Using either of these two switches for both functions would require adding at least one double-throw relay to one of the circuits which would seem to me more complicated than sticking with two separate switches.

Don