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  #1   IP: 172.58.121.61
Old 07-02-2021, 12:02 PM
TomH TomH is offline
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What Is This?

In the attachment is pictured a white disk with two screw mounts for ~16 AWG wire connections. It looks to be ceramic or Bakelite, mounted just aft of the fuel pump, and where Moyer would have the oil pressure safety switch installed.

My multimeter shows an infinite resistance between those two screw terminals.

The nearer screw mount currently connects wires between the starter solenoid and the positive terminal of the coil. The further terminal connects the wire from the electric fuel pump to a wire connecting to the positive terminal of the coil.

Anyone know what this is?

More importantly: can I safely bypass it?

I suspect it’s just an old terminal block, but am concerned that it might provide some functionality.

Thank you!
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  #2   IP: 104.174.83.118
Old 07-02-2021, 01:48 PM
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ndutton ndutton is offline
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That is an oil pressure safety switch for the electric fuel pump that also shows in the picture. It should measure continuity when the engine is running, no continuity with the engine off. It is a USCG safety requirement for a gasoline engine with electric fuel pump. Four wires attached seems odd however, you might want to trace them down. Typical installations have two wires: one from the ignition and one to the fuel pump.
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More importantly: can I safely bypass it?
No, SAFELY being the operative word. The only purpose for an oil pressure safety switch is safety.
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prior boats 1987 Westsail 32, 1970 Catalina 22
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Last edited by ndutton; 07-02-2021 at 02:25 PM.
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Old 07-03-2021, 07:41 AM
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ndutton,

Thank you for the helpful reply.

This leaves me wondering if this is wired correctly.

The current wiring places:
  • one terminal in line between the coil positive terminal and the starter solenoid. (On the solenoid, the wire connects to the top of the two 5/16 (?) inch terminals…opposite the terminal that Moyer indicates should connect to the ignition switch with a yellow/red stripe wire. I believe it’s connecting to the R terminal, though I can’t see any imprint on that side.)
  • the other terminal on this oil pressure safety switch is inline between the coil positive terminal and the fuel pump.

Any thoughts are appreciated.

Last edited by TomH; 07-03-2021 at 09:31 AM.
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  #4   IP: 104.174.83.118
Old 07-03-2021, 09:31 AM
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The previous owner was intending to use the starter's R terminal to give the fuel pump a boost at start-up but unfortunately his miswiring missed the mark. In fact, it's so miswired that the OPSS currently serves no purpose.

Check out the drawing in this post. It shows proper OPSS wiring incorporating the R terminal.
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