Mercruiser Electrical - How It Works (Read the Description)
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- Опубликовано: 7 сен 2024
- In this short video I’m describing the electrical starting and charging system on a Mercruiser 4.3 V6 with an electric fuel pump. V8s are similar.
In other videos I describe the Thunderbolt Ignition systems which due to their age are beginning to malfunction causing strange issues like no start, hard to start, and no power due to poor timing advance.
To solve troublesome ignition problems, I sell a replacement kit based on a GM ignition module. See my “SPARKIE THE EEL” video series here:
• SPARKIE The EEL - Delc...
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This video just saved me! Short and to the point. Easy to fallow and troubleshoot my starter problem. Just removed my starter and THREW it overboard!! Thank you for a short but great video! Just liked and subscribed
i’m having a starter issue as well
Hello
Are all the threads installed in the same screw, red, orange, yellow and purple?
Are all the threads installed in the same screw, red, orange, yellow and purple?
Please reply, thank you❤❤❤❤❤❤❤
Gosh that super information but you speak so blooming fast have to keep watching it to try to keep up with you. Slow it down mate, but thanks again for the info. Invaluable.
bless ur soul
I have 2 wires( a black and a yellow) going to a plug connector on the temperature alarm (the one closest to the alternator side) is this correct? Also, i have the white w/ black and black on the other side that i cant figure out where they go
One nail only
Do you know where I can find an engine schematic breaking down every component in correlation to placement on the engine?
It's a 1993 Mercruiser 4.3, bought it with heads/ intake/ alternator/ carb, Yada Yada removed and now it's fixed but weary on some parts he had in a baggie
If you have the serial number of the engine go to www.marineengine.com and put in the serial number. That will bring up a schematic of your system. The serial number is a metal tag on the block just above the starter.
@@moccasinmarine appreciate your time!!
I will say that 95% of the bolts in a GM small block (4.3 is a small block with 2 cylinders less) are 3/8”x16 of varying length.
Why would I not be getting power to my fuel pump? My fuel pump works when jumped from the battery. No power from from the purple wire that goes to the fuel pump from the oil pressure switch while engine running but does have power on the purple wire that comes from the starter to the oil pressure switch. any ideas?
I have the same problem. Tested the oil pressure switch, ohms and volts are good, diaphragm was bad. Jumped the switch with a paper clip and my fuel pump worked/buzzed. I believe the starting/default position for the oil switch is open, then gets 4psi to close circuit, passes juice/volts to fuel pump. Engine doesn't start, then with key in run position, not crank position, fuel pump is buzzing. So this must mean that after cranking, the motor maintains at least 4 psi... right? Is that possible:? 1 crank, 2 build pressure, 3 no start, 4 pressure of 4+ psi remains ?
@@mtbristol I'm pretty sure my oil pressure switch is bad. There should be a lot more than 4psi when the engine is running. If you only have 4psi of pressure then you have bad motor. Mine runs at 65psi of oil pressure when running. I just jumped the wires together so I have fuel as long as the key is on. My block is cracked badly in the valley. Fills the engine with water within 5 minutes and then a milk shake comes spewing out the breather hoses. Got the intake off now. Getting ready to JB weld it and see what happens. If it doesn't work then I'll be ordering a reman long block.
So the purple wire at the starter is supposed to have 12v with the key in the run position?
That purple yellow wire runs to the back of the alternator as well??? What’s that for?
i have this boat, where does the black wiring go running parallel to the purple wire?
i have two loose black wires that are unplugged and cannot race them to where they go...
I would need a photo to answer this question. Send me a photo to gmefiguy@gmail.com
@@moccasinmarine coming at cha! much love!
@Moccasin Marine LLC did you get an answer to this question?
I would also like to know what the answer was as I have the same. A black wire and a purple wire that can't be accounted for.
Are all threads installed in the screw, red, yellow, orange, and purple?😢😢😢😢
So if the fuel pump doesn’t turn on would it be the oil pressure switch is bad?
Either that or a bad pump.
Is the purple wire to the coil 12 volt or reduced 10 or 9 volt (with a resistance)?
On some it is and some it’s not. Depends on what year it is.
@@moccasinmarine 1991, Mercruiser 5.7 (carb) with Thunderbolt 4 ignition
I am getting no engagement when I turn the key, completely zero. New starter, battery seems good.. what do you suggest I start with looking at
Neutral safety switch in shifter will not let start signal reach the starter relay. If that checks out connect 12v jumper wire to starter relay yellow/red terminal. If relay doesn’t engage either bad relay ground or bad relay. If relay does engage but no starter spin you have a bad starter or bad yellow red wire to starter.
However, before any of the above, see if any accessories work in the gauge cluster, like bilge pump or blower or gauge lights, etc. if none of that works you may not be getting power to the steering console. That power is fed through pin 6 of the boat to engine harness connector. Pin 6 is fed from the main fuse at the battery cable connection at the starter.
So where is the actual alarm located that the tan and blue wires lead to? I purchased a boat with a ‘94 4.3lx alpha one gen 2. The temp and oil pressure gauges work on the dash but there is no low oil pressure alarm that sounds when starting the boat.
The alarm is up under the dash panel. It sounds anytime the tan/blue stripe wire is grounded.
Someone had installed some type of rocker switch at my alarm under the dash
Hello, I'm installing a Holley Sniper EFI on my MerCruiser 5.7, Would the purple, yellow wire you described in your video be a good source for a constant source 12 Volt connection for my Holley Sniper EFI? Also, I'm installing a MSD ready to Run distributor, how would I connect the cutoff switch wire to which distributor wire.
I would go directly to the battery.
@@catfisher420 I figured it out, thanks.👍🏿
Got a question for ya. Got the same engine in my maxum. 4.3 But my problem is my ignition switch is dead. It won’t do anything for the motor. So I replaced the starter relay with a new one and I did the old screwdriver trick and it did kick over the motor. So I know it’s good. Probably was even bad in the first place. But my Accessories still work on the key switch but that’s it. Could the ignition switch be bad?
The starter circuit at the ignition switch is a different contact. The starter contact on the switch only turns on the starter relay nothing else. The starter then powers up the ignition through the purple wire on the starter. Once the engine runs and you let go of ignition switch the other contact (RUN) in the ignition switch powers the ignition and accessories on the engine and console.
@@moccasinmarine so how can I test the ignition switch to check for fault? Take a test lead from the yellow/red wire to the purple wire? Then turn key as if cranking?
I have no power to my pump. 2002 Bayliner Capri Carbed Mercury 5.0. Is that oil pressure switch suspect as faulty? Also, I can find no pump relay or fuses dedicated to the pump.
There is no relay because the pump is powered directly through the ignition switch, then through the driver kill switch, then through the oil pressure switch. During starting the pump gets power from the starter but during run the power comes through the oil pressure switch.
@@moccasinmarine Thank you. I'm on the final step with starting it. Does the fuel system need to be primed after replacing the fuel filter/water separator?
@@rsw0331usmc yes, jumper oil switch wires together, turn ignition switch on and pump should run. Run until fuel squirts from accelerator shots in carburetor. Turn off ignition and remove jumper.
@@moccasinmarine Thanks again. I did try jumping the pump directly with jumper wires from the battery. The pump did run in this condition but I still had no fuel delivery. I disassembled everything and looked for obstructions. There was not a drop in the filter, it did not draw any fuel at all. I wound up back-bleeding it with a large syringe and hose from the carb fitting back. That worked.
What wires go to the ignition coil
Purple and gray. I showed them in the video.
Double purple on positive double grey on negative
Please reply, thank you😊