Fuel Pump Wiring

[Lloyd R]

Hello. I'm in process of trying to get this new to me boat running safely.
My question has to do with proper wiring of the fuel pump. I have a 1996 Crownline 225br with a 454 Mercruiser. (serial # F810329)

I replaced the electric Edelbrock fuel pump 2 times. The previous owner had wired it direct from the ignition switch and grounded it to the battery. Not sure if that's why it burned up. But I've have read that this is unsafe.

My questions:

1. Should the purple wire be connected to the + post on the coil? (see pic1)
   1. Can you tell me what this wire does?
2. Should I run a wire from + post on coil to oil pressure switch or should I run a wire from yellow/purple wire? (see pic 2)
3. In pic 3, I think this is the oil pressure switch. Can you recommend how I would tie this in from the starter I terminal? The oil pressure switch only has one blue wire. (see pic 3)

Thank you for your help.

 

[Bondo]

Ayuh,...... Welcome Aboard,..... That Is quite the cobb-job,.....

The fuel pump is powered from 2 different circuits,.....
While the motor is crankin' on the starter, it's powered from that tiny terminal on the starter, which doesn't have a nut on it in yer picture,....

Once the motor starts, 'n you release the key, it's powered by the ignition circuit,...... I'd pull power from the purple wire right there at the electric choke in yer picture,.... Then ya gotta run it over to the portside of the motor, way down low towards the aft is a pressurized oil port, by the filter boss, where you need a pressure switch, then back to the fuel pump's power wire,.... ground can be anywhere convenient(on the block),....

I believe the thingy with the blue wire is a knock sensor, which is supposed to be piggybacked into the block drain,....

 

[Lloyd R]

Thanks Bondo.
Is this the aft pressurized oil port? (pic 4)
If so, you mention that I need a pressure switch. Would I tie into the existing switch or add a new one?

 

[alldodge]

Your pic 4 is the oil gauge sender and does not have anything to do with the fuel pump

Thanks for the serial number.
Your motor came with a mechanical fuel pump. The electric pump was added later. The pump was mounted on the raw water pump, item 1
https://www.mercruiserparts.com/bam/subassembly/31806/2345/12

To install an electric safely it need a oil pressure switch. This is a simple way to do it

 

[Scott06]

Thanks Bondo.
Is this the aft pressurized oil port? (pic 4)
If so, you mention that I need a pressure switch. Would I tie into the existing switch or add a new one?

You need to add a new switch that is the oil gauge sender with one wire on it.

If you look at parts 41,42,43 in this diagram they use a 1/8" npt T to put the sender (41) and oil pressure switch (42) into the oil system. You can reuse your sender and get a 1/8" T and pipe nipples to attach the switch.

https://www.marineengine.com/parts/mercruiser-sterndrive-parts/50l-carb-alphabravo/0w300010-thru-0w309999/electrical-components

Here is a OEM merc switch with wiring pigtail https://www.michiganmotorz.com/mercruiser-oil-pressure-switch-kit

 

[Lloyd R]

I like simple. Thanks!

1. Where would I mount the switch?
2. Would you recommend any particular switch?
3. Also, should I remount the purple wire in pic 1?

Really appreciate all the help!

 

[alldodge]

Sorry Scott I retract
the switch will work

 

[alldodge]

1. Where would I mount the switch?
2. Would you recommend any particular switch?
3. Also, should I remount the purple wire in pic 1?

1. Remove the sender in pic 4 and install a brass Tee. Reinstall sender on one side of brass Tee. Other side of Tee install new oil pressure switch

2. Scott has link to switch

3. Yes, the purple wire must be mounted on the coil + side

Note you must have a small post on the outside furthest away from block on your starter for this to work. This is where it gets power when motor is cranking

 

[Lloyd R]

Wonderful. Thanks very much. Time to go get the parts and go to work!
Appreciate you help!

 

[Scott06]

https://www.justanswer.com/boat/5y7cc-wirer-electric-fuel-pump-installed.html

this is a link to the merc wiring diagram shows how the OEM two terminal switch (6) is wiring into the harness and splice from starter terminal to fuel pump (7).

 

[Lloyd R]

Thank you! I appreciate your help and the references. I have the part ordered.
Your guys helped me to do it the right and safe way.

 

[Lloyd R]

Just to be sure, I installed the 2 wire switch from a T at the oil pressure switch.

1. On one side of the 2 wires switch - I run to the Purple ignition wire?
2. On the other side of the 2 wire switch - I run wire to the small stud on starter solenoid then to the fuel pump?
   1. Or should I make a T and one end to the starter solenoid and the other to the Fuel pump? Or can I do either?

 

[Scott06]

Just to be sure, I installed the 2 wire switch from a T at the oil pressure switch.

1. On one side of the 2 wires switch - I run to the Purple ignition wire?
2. On the other side of the 2 wire switch - I run wire to the small stud on starter solenoid then to the fuel pump?
   1. Or should I make a T and one end to the starter solenoid and the other to the Fuel pump? Or can I do either?

Purple wire to pressure switch off the switch have a splice/T one leg to starter other leg to fuel pump. This way the fuel pump gets powered either by starter when starting or thru the Switch when ignition is on (12 v to Purple wire

 

[Lloyd R]

Great, Thank You!