Oil Pressure Safety Switch questions???

[JOHN COOKSON]

You're On The Right Track

So I'm assuming once I get the new OPSS from Moyer, I can find out which one is ground on the existing switch and eliminate with to go with the typical 2 wire connection...

The ground side or circut is usually kept seperate from the hot circut. To have the ground side and hot side on the same switch is well......atypical.
The cut wire may have been the ground wire to the instrument cluster. You can see this for yourself or post a picture. Each gauge should be grounded. If the wire that was cut does come from the gauge cluster as a ground wire the other end went to engine ground or a buss bar then on to battery ground.
Have you consulted the "drawings and schematics" section of the forum?

TRUE GRIT

[hanleyclifford]

If the switch has three terminals it is most unlikely any of them have to do with ground. It is more likely two of them are one side of the switch providing two + inputs to run the pump - possibly one from the ignition circuit and an override from "R" on the starter solenoid.

[southcoasting]

Yeah, on the gauge itself, there are three connections, one is already grounded...The other is not a ground that I would assume goes to the switch and third connection is the copper oil line...

[hanleyclifford]

What's needed here is a wiring diagram. Neil, are you on station?

[ndutton]

What's needed here is a wiring diagram. Neil, are you on station?

It's my pleasure.

[edwardc]

Yeah, on the gauge itself, there are three connections, one is already grounded...The other is not a ground that I would assume goes to the switch and third connection is the copper oil line...

If your gauge has a copper oil line going to it, it's a mechanical gauge, and needs no power to function. The only leads going to it should be for the illumination lamp. One wire should go to ground, and the other to someplace that is energized to +12 when the ignition switch is turned on.

[hanleyclifford]

The diagram posted by Neil shows the basic wiring for the fuel pump but does not include the override circuit from solenoid "R". Since your OPSS has three terminals and thus possibly the override, additional wiring details may be needed. Thank you, Neil; as always ready with the good stuff.

[ndutton]

Fyi

It's my opinion the override adds unnecessary wiring complexity to a basic A-4. There is ample residual fuel in the carb bowl to get the engine started without any help from the fuel pump. Once started the oil pressure rises so quickly it seems the fuel pump starts instantly (I have a fuel pump indicator light on my engine panel so I keep a close eye on it).

If you're a keep it simple sort, I'd avoid the start switch override altogether. Simpler to wire in the first place, simpler to troubleshoot later.

[southcoasting]

I see...That makes sense...

Thanks everyone...

I will try to simplify this setup and see what I come up with...Will keep you guys posted...

[southcoasting]

Thank you all SO MUCH! I was able to troubleshoot and figure out what is what with your help...You guys are the "A-BOMB"!

So, I was able to do quite a few things recently to get this thing ready for next week's on "the hard start". Trying to get the boat launched by end of April...

While getting things ready (normal maintenance as recommended here before first season start), I realized Hanley and others were right about the OPSS wiring...One wire was coming from the starter and the other from the coil...So I will be wiring the new replaced switch with only the +Coil wire and remove the +Starter wire to keep it simple...

I also confirmed the black wire from the first picture coming from the oil gauge seems to be a power cable, prob for the gauge light as edwardc suggested...

Buying some batteries this weekend and looking try to start this thing for the first time next week...Will keep you guys updated on the progress...

[hanleyclifford]

In 99% of cases Neil is right about not needing the override circuit from the "R" terminal on the solenoid to get the fuel pump running before oil pressure is achieved. In fact on my boat I don't want fuel pump or ignition until at least 7 psi oil pressure is attained. FWIW, sometimes the "R" terminal is used to provide a coil resistor override to "goose" the voltage to the ignition during cranking.

[magi]

OPSS Jumped Out

How bad of an idea is running with the OPSS jumped out ?

[msmith10]

The purpose of the OPPS is to turn off the fuel pump if the engine is not running, thus preventing the pump from forcing fuel into the carb and potentially spilling into the bilge. If I were away my home port and the OPPS malfunctioned, I would bypass it to get home, then fix it. I would not leave it bypassed as this would create a potentially unsafe condition, would certainly void the insurance, and is just an unseamanlike thing to do.
It's such an easy fix- screw out screw in.

[joe_db]

It's my opinion the override adds unnecessary wiring complexity to a basic A-4. There is ample residual fuel in the carb bowl to get the engine started without any help from the fuel pump. Once started the oil pressure rises so quickly it seems the fuel pump starts instantly (I have a fuel pump indicator light on my engine panel so I keep a close eye on it).

If you're a keep it simple sort, I'd avoid the start switch override altogether. Simpler to wire in the first place, simpler to troubleshoot later.

I have a manual button for the override. If I have run the fuel out after shutdown, I use it. If the engine was just turned off still showing fuel pressure, it is not needed.

[capnward]

More mechanical fuel pump advocacy

Just a reminder, if you have a mechanical fuel pump (there I go again!), there is no need to override or bypass anything electrical to get fuel pressure with the engine off. You just manually pump the bail underneath the pump until the resistance disappears and your fuel pressure gauge reads 3 or so. This way the engine will start sooner and not have to crank for a while to get fuel from the tank to the carb. And as Joe said, if you have been running recently there will be adequate fuel in the carb to start.