No power to Coil

[AKBASSKING]

Need those who can help me trouble shoot here. Put your electrical hat on.

Replaced all the exhaust tubing today and got everything ready to start the port engine. It had been 7 months. Put fresh gas in the tank and sprayed a little starting fluid in the carb.

Had the admiral crack it over and nothing. Pulled the coil wire and no spark. Off to the book and the wiring diagram. The coil gets it power from the back of the alternator. 12vdc comes into the alternator from the wiring harness. had 12vdc coming in, but nothing coming out.

I ran a hot wire to the coil, hit the key and boom it fired right up. With it is running I get good voltage out of the alternator according to the gage.

Bad alternator?

 

[fc3]

Bad ignition switch, bad wiring or bad run resistor.

 

[unlvrebel]

Not sure about the possibility of a bad ignition switch as the unit turned over with the bad wire and started up with a bypass wire. My be is that there is some inline fuse in the wire. I've run across this on older (70s) Chevys that I have serviced. Somewhere in that run there was a fuse to protect against power surges. Sometimes I would chase them down and sometimes I would just create another run. Does the wiring diagram show an inline fuse anywhere?

 

[midway]

You can lose the ignition or accessory side of the ignition switch and still crank the engine over with the starter. If you lose the ignition side no power to coil, the accessory side no items wired to that terminal will work. I have also had wiring problems at the main harness plug in my old boat (1987), it also lost the resistor.

 

[unlvrebel]

You can lose the ignition or accessory side of the ignition switch and still crank the engine over with the starter. If you lose the ignition side no power to coil, the accessory side no items wired to that terminal will work. I have also had wiring problems at the main harness plug in my old boat (1987), it also lost the resistor.

I ran a hot wire to the coil, hit the key and boom it fired right up.

OK, but he bypassed the wiring harness with a jumper wire and used the ignition. To me, that says that the ignition is working.:huh:

 

[midway]

By running the hot wire he did bypass the ignition side of the switch, he used the start side to crank the engine, it ran off of the hot wire, pull the hot wire and it would shut down. If I understand his post the switch would spin the engine over it just would not fire up and run, when he added the hot wire to the coil it would then run. Something in the ignition side of the circuit is not working, ignition side of switch, harness, or the resistor if it has one.

 

[osd9]

I'm going to pull this one out of thin air, I don't remember all the details...but...back in 1986, a dock neighbor had a very similar problem on a 1984 230WE. We got out the shop manuals and looked over the wiring diagram. There's a 'purple' wire in the ignition circuit and it goes from guage to guage behind the dash. One of the 'purple' wire lugs was lose on the back of one of the guages. We tightened it up and .......Brrrrruuummmmm!!!

 

[AKBASSKING]

No accessory side on the switch.

Did a little troubleshooting last night and this is where I am. You all are correct when I bypass the switch and go to a hot wire to the coil it fires right up using the ignition switch to crank. Pull the wire to stop the engine.

The stbd engine runs fine. With key off, no voltage to the coil. Key on 12vdc on coil. Nice thing about having 2 engines is that you can use the good one for trouble shooting.

Took the ignition switch panel out and switched the wires over to the stbd switch. Same problem, no difference. Power on the purple wire in run position.

This tells me I have a wiring issue between the ignition switch (purple) and the coil. The one place to break it down is on top of the engine where there is a connector plug. Problem is the plug is all rusted and will be a bear to get a part.

According to the MercCrusier shop manual it is a straight run from the switch to the engine, no fuses or resisters. So over the next few days I will be chasing electrons to see if I can find the break.

 

[tdappleman]

Not sure exactly which engines and ignition you have so this will be some things I did troubleshooting a few issues on mine. If the connector plug you are referring to is similar to mine it could very well be part of your problem - it is the main wiring harness going to the engine. Mine is a round plug with 9 (I believe) connectors in it. I had intermittent problems and at the advice of the forum took the connector apart, cleaned and dried it out and it's been great since. One word of caution is the hose clamp on the connector - do not overtighten it as it can crush the connectors inside. While you are cleaning connections - clean everything and spray with something like WD40 or PB Blaster. I routinely give mine a shot of PB Blaster about every 2-3 weeks - all connectors and battery terminals and it keeps corrosion and rust at bay.

The purple wire should have power to it when key is on - it is the power which energizes the coil, connects to the alternator, goes to the electric choke (if equipped) and also connects to the oil pressure shut off switch. The other side of the oil pressure shut off switch on mine is purple/yellow and that goes to the fuel pump and starter solenoid.

So - when the key is on you should have power at the coil, alternator, choke and one side of the oil pressure switch. If you have power at these locations and it wont start you may have a bad slave solenoid. There are ways to test that - but it can create sparks.... Here's a link to some directions I found when troubleshooting mine but certainly take care to ventilate the bilge well and be careful with potential sparks.

 

[AKBASSKING]

Thanks Travis.

Funny ending to this story. My sone came down from Norfolk to spend the weekend with us. He may not come back! I sent him to the bilge! We replaced 2 floats switches and all the bilge hoses!

Tonight we were sitting on the bridge drinking an adult beverage when I noticed there were 2 toggle switches. Port stop/run/start! Funny the waring diagrams don't show this.....

Yep, had the port engine switch in the "stop" position. Moved it to run and yes I now have power to the coil.

Man, the hours I spent troubleshooting......

Well at least I got all my bilge pumps taken care of....:smt009

Now to a new problem, new thread....

 

[unlvrebel]

Thanks Travis.

Funny ending to this story. My sone came down from Norfolk to spend the weekend with us. He may not come back! I sent him to the bilge! We replaced 2 floats switches and all the bilge hoses!

Tonight we were sitting on the bridge drinking an adult beverage when I noticed there were 2 toggle switches. Port stop/run/start! Funny the waring diagrams don't show this.....

Yep, had the port engine switch in the "stop" position. Moved it to run and yes I now have power to the coil.

Man, the hours I spent troubleshooting......

Well at least I got all my bilge pumps taken care of....:smt009

Now to a new problem, new thread....

Ahhh... The kill switches strike again!!!:smt089 Not one of us asked if you checked those first!:smt021

I'm betting that will be the first thing you check going forward on ignition related problems. Experience is the best teacher. Congrats on getting your bilge taken care of!:thumbsup:

 

[AKBASSKING]

Ahhh... The kill switches strike again!!!:smt089 Not one of us asked if you checked those first!:smt021

I'm betting that will be the first thing you check going forward on ignition related problems. Experience is the best teacher. Congrats on getting your bilge taken care of!:thumbsup:

Yeah, not one!!!LOL Not even me. What gets me is the schematics don't even show it!!:smt009

Found out my search light works kind of. It turns on, goes up and down and turns left......not right......where is that extra switch......I know it is here somewhere

 

[Integrity]

Does anyone have an idea where one can buy replacements for the stop/run/start switches? One of mine is bad and I haven’t had any luck at normal switch supply houses.