1990 Cruiser 3.0 Carter Electrical Pump wiring issues

[TheTaxButler]

• 1990 Sea Ray BR160 Electrical Fuel Pump
  
  Hello to all the the wonderful people in this forum. I am a new boat owner, having grabbed a 1990 Sea Ray BR160 off craigslist for about $350 as a project boat. Looked like the old pump failed so I opted to switch over to an electrical fuel pump going forward.
  
  I have an oil pressure switch teed with the oil pressure sender. I have looked extensively at other forum posts on how to wire the pump and switch system. I have also sent a wire from the switch and INTO the purple ignition switch wire on the wiring harness. Other forum posts, especially by the venerable Don S have shown a schematic which shows to send a wire to the Starter Solenoid at the purple/yellow wire. The problem is that my Mercruiser 3.0L AlphaOne does not have a purple/yellow starter wire on Solenoid. It has the regular Red, orange and Red/Yellow wires on the Solenoid (the latter of which is in the opposite position of where Purple/yellow would be. I went ahead and attached the wire to WHERE the purple/yellow would have been on the diagram. Mistake?
  
  When I turn the key from off, the pump does not come on but it will come on after I have tried cranking the unit. Is this correct operation? If it is not sending pressure until after I have stopped cranking, I don't see how that would help with starting or filling the carb bowl! I have read another forum with another Mercruiser that seemed to have the same setup with another post by the Venerable Don S indicating that maybe they should try using the red/yellow wire on Solenoid. Should the pump be working only when trying to crank, when I first turn the key on from "off" position or both? I can send pictures later if needed. Any help is appreciated for the beginner boater!

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[achris]

If you attach directly to the red/yellow, you won't be able to disengage the starter once oil pressure is up.. The diode in the circuit below will prevent that. That diode is about 50c from any electronics shop (I buy them in packets of 10. I use them as 'solenoid savers' as well.)

And yes, you should NOT hear the pump running until you have either oil pressure up or the starter cranking the engine.

Chris.........

 

[TheTaxButler]

Just a clarification for the relay: where should the main power to relay be coming from? The Slave solenoid? Would this be 4 or 5 pin? Or would power be coming from oil pressure switch? Just trying to figure out which wires will correspond to relay terminals.

 

[TunaFish389]

The coil side of the relay will have yellow/red after inline diode and ground to other side. The switch side of relay will be red/purple and positive to pump. Yellow/red and red/purple coming off of slave solenoid.

 

[TheTaxButler]

Hey guys I appreciate all the help on this issue and it all seems much clearer to me. The only question I have left after the above answer is where the Oil Switch wire ties into all this with the relay. If power is drawn after diode on Red/Yellow and switch is activated from Red/Purple where would I be splicing the wire coming from "S" on oil switch? I think we are just about there! Apologies for the questions but despite past wiring experience it's my first time using a relay.

 

[alldodge]

The switch in the diagram above is a SPST type and just open/close position.

coming from "S" on oil switch?

With an S terminal it sounds to me you have the SPDT switch that most most use to wire up a new fuel pump without a relay. Need to identify which switch you do have

As such you would not use the S terminal and only use the C (common) and the R or NO (Run or normally open) contacts connected between the purple and relay/diode

 

[TheTaxButler]

ALLDODGE* My oil pressure switch is 3 pronged: "I" which is supposed to splice into purple Ignition wire, "P" which is supposed to be power directly to the Fuel Pump and "S" which is supposed to draw power from the Starter Motor with an 10amp Fuse in between. Originally, I was thinking of not using a relay and I have read elsewhere on this forum that it can be beneficial for the entire system. I know the pump works because after cranking there is a couple second delay and the pump starts sending gas. As stated above, my Mercruiser does not have a purple/yellow wire on the Starter Solenoid as I have seen on other Mercruiser diagrams which led me to find out where to draw that power from.

From what I am understanding in the diagram provided by Achris is that I should totally bypass the Starter Motor Solendoid and instead draw power from the Slave Solenoid and then send power to the pump through a relay so as not to overdraw & shorten product/battery life. Can I still use my Pressure Switch to achieve this?

 

[alldodge]

The drawing above will work

The drawing below is how most folks change over to electric. To use your switch replace
I = NO (Purple)
P = C (Fuel Pump)
S = N (Yellow/Red) Normally closed contact

 

[TheTaxButler]

Thanks for the example AllDodge. For my Starter Motor, I only have Yellow/Red wire there on the side terminal. I was warned by Achris that drawing from that source would prevent Start Motor from disengaging after oil pressure build-up. He advised to use an In-Line Diode if drawing from that source (or in his diagram the Slave Solenoid). Should this same method be used with the starter motor power source?

 

[alldodge]

Thanks for the example AllDodge. For my Starter Motor, I only have Yellow/Red wire there on the side terminal. I was warned by Achris that drawing from that source would prevent Start Motor from disengaging after oil pressure build-up. He advised to use an In-Line Diode if drawing from that source (or in his diagram the Slave Solenoid). Should this same method be used with the starter motor power source?

Agree with your statement, but (always a but) using the switch you have and the wiring diagram I posted this is not an issue. Reason being, when pressure builds up the switch opens the contact between C and NC contact, and makes contact with C and NO contact. Also when the key is released back to run, the slave solenoid disengages and there is no power on the Yel/Red going to the starter solenoid

My comments are not an attempt to have you change one way or the other, just info as for the type of switch you have. As I said in post 6

As such you would not use the S terminal and only use the C (common) and the R or NO (Run or normally open) contacts connected between the purple and relay/diode

This will allow you to use your current SPDT switch, and use only one side of it as a SPST switch and wire as acrhis posted

 

[alldodge]

This should help clarify

 

[achris]

Check the current carrying capability of that switch. Then check the current drawn by the pump... If the switch isn't man enough, put a relay in, use the current from the switch to pull the relay, and supply the relay (via a fuse) from the feed side (red/purple) of the slave solenoid....

 

[TheTaxButler]

Thanks for all the feedback AllDodge and Achris. I have purchased an inline fuse holder just in case and it sounds like I have a couple ways to achieve this but it is all much clearer now. Will go out to the boat tonight or tomorrow morning and get everything wired up & see how its working.

If everything goes successfully, I may add pictures and/or a link to video in this thread for others embarking on the same journey.

Thanks again guys, really appreciate you taking the time to help me figure this out!