1995 Mercruiser 3.0LX Alpha One - EST Ignition Coil: No 12V

[Robjr67]

Good Day. I'm very thankful for this website for as I've found alot of information about my ignition problem, but have come to the point where I have to ask a question.

I've got a 1995 Mercruiser 3.0LX Alpha One that I've had for over 6 years and has been a very reliable boat. Throughout the years I have "no spark" issues, but wouldn't last and would start. Until this year, it has no spark at all. I narrowed it down to the ignition module and replaced it and it started up. I took it our one last time prior to winterizing it and it didn't have the power. Didn't come up to plain as fast etc., so I headed back and in a long no wake zone it died. No, spark and wouldn't start. Got towed back...

I've used information from this site for troubleshooting and found I don't have 12 volts from the purple wire going into the coil. So, I disconnected the grey connector that contains the purple and grey wire and jumpered a wire from a 12 volt source and put it the + side of the coil. I got spark and it started. To include, it was consist. Kept checking the spark to the coil and kept starting up.

So, my question is what could be causing not to have 12volts to the purple wire? Tachometer? I really appreciate your time and help.

Regards,

 

[joey nathan]

Re: 1995 Mercruiser 3.0LX Alpha One - EST Ignition Coil: No 12V

I believe the purple lead is hot +12VDC when the key is on. So your problem could be an intermittent key switch. Good place to start troubleshooting anyway.

And then trace the purple wire all the way from the key back to the engine - possible the wire is broken/frayed along the way somewhere...

 

[Robjr67]

Re: 1995 Mercruiser 3.0LX Alpha One - EST Ignition Coil: No 12V

I believe the purple lead is hot +12VDC when the key is on. So your problem could be an intermittent key switch. Good place to start troubleshooting anyway.

And then trace the purple wire all the way from the key back to the engine - possible the wire is broken/frayed along the way somewhere...

Thanks for the reply. Yes, there is suppose to be 10+VDC with the key is on according to troubleshooting guides. I will check the purple wire for continuity. Is there any other known cause besides the switch to make the purple wire not to have 12VDC? Thanks in advance...

 

[Don S]

Re: 1995 Mercruiser 3.0LX Alpha One - EST Ignition Coil: No 12V

Is there any other known cause besides the switch to make the purple wire not to have 12VDC?

Lanyard kill switch, loose or corroded connection in the connectors and connections from the coil to the switch.

 

[Robjr67]

Re: 1995 Mercruiser 3.0LX Alpha One - EST Ignition Coil: No 12V

Lanyard kill switch, loose or corroded connection in the connectors and connections from the coil to the switch.

With a busy week, I found a little time to work on the old girl. I got under the dash and checked and found 12v (purple wire) at the switch and lanyard. Initially thought I found the problem when a blk wire came out of the connector going to the switch which I corrected as well, but still don't have 12v from the purple wire going into the ignition coil. While I was in the back of the boat I noticed that the blk wire going to the alternator was not connected just hanging there. I was getting to dark/late to correct and will correct today. But, my question is, will the blk wire (ground) not connected to the alternator cause not having 12v on the purple wire at the ignition?

Thanks again,

 

[Don S]

Re: 1995 Mercruiser 3.0LX Alpha One - EST Ignition Coil: No 12V

The black wire has nothing to do with it. You have a problem with the purple wire. Power on the purple wire starts at the ignition switch and ends at the coil (and a couple of other places). If the kill switch is ok, and you have power out of it, then you have a bad connection or a broken wire somewhere between the kill switch and the coil. Could be nothing more than a corroded connection at the main harness connector on the engine.

 

[Robjr67]

Re: 1995 Mercruiser 3.0LX Alpha One - EST Ignition Coil: No 12V

The black wire has nothing to do with it. You have a problem with the purple wire. Power on the purple wire starts at the ignition switch and ends at the coil (and a couple of other places). If the kill switch is ok, and you have power out of it, then you have a bad connection or a broken wire somewhere between the kill switch and the coil. Could be nothing more than a corroded connection at the main harness connector on the engine.

Thanks Don for the quick reply. Looking at the wiring diagram it made sense that the ground on the alternator didn't have anything to do with the 12v, but wanted to double check. As you mentioned above the 12v ends at a couple of other places like, Electric Choke, Shift cutout switch, igntion coil and alternator. I also, noticed that the alternator's purple wire is not connected as well. Is that an issue? Seems I remember it being like that since I've owned the boat, but again wanted to double check.

As you mentioned I will start to trace the purple wire back to try and find the problem. Worst case scenario, could I run a dedicated correct gauge wire from the ignition switch to the ignition coil as a work around? Again Thank-you.

 

[Don S]

Re: 1995 Mercruiser 3.0LX Alpha One - EST Ignition Coil: No 12V

I also, noticed that the alternator's purple wire is not connected as well. Is that an issue? Seems I remember it being like that since I've owned the boat, but again wanted to double check.

You probably don't have the OEM alternator, if you did, it wouldn't charge without that wire hooked up.
If you turn the ignition key to the run position, do you have voltage on the choke or alternator purple wire? They all come together in one splice in the wiring harness.

 

[Robjr67]

Re: 1995 Mercruiser 3.0LX Alpha One - EST Ignition Coil: No 12V

You probably don't have the OEM alternator, if you did, it wouldn't charge without that wire hooked up.
If you turn the ignition key to the run position, do you have voltage on the choke or alternator purple wire? They all come together in one splice in the wiring harness.

Not sure if it's the OEM alternator or not, it's black. Thinking that is not because it seems like I do remember the purple wire not being connected.

I will check for voltage at the choke, cutout switch and alternator tonight. The findings should help narrow the problem. More to come and thanks again.

 

[fat fanny]

Re: 1995 Mercruiser 3.0LX Alpha One - EST Ignition Coil: No 12V

As Don said you need to test for current at the ends of each purple wire. I know because I have went through this myself and it was kind of a pain because I ended up removing the whole wiring harness and un wrapping it and testing for continuity then re- wrapping it to eventually find out I had a bad ignition switch but it did give me a better understanding of the electrical system of my rig and I know it's bullet proof for now at least. Just make sure you lube every connection with dialectric grease and tighten and replace all suspect connections.

 

[Robjr67]

Re: 1995 Mercruiser 3.0LX Alpha One - EST Ignition Coil: No 12V

You probably don't have the OEM alternator, if you did, it wouldn't charge without that wire hooked up.
If you turn the ignition key to the run position, do you have voltage on the choke or alternator purple wire? They all come together in one splice in the wiring harness.

I checked all the wires tonight and didn't have 12 volts from the electric Choke, Shift cutout switch, igntion coil or the alternator. So, I went up front and start testing the purple wire back. I was getting 12 volts from every place I checked that I could reach. Got to the back of the motor and started to find the purple wire from the plug and thought I would check the 12volts at the ignition before I started getting into the loom. I was surprised to see 12volts...! Went to start it and it started right up. I was like great...I still don't know where the problem is. So, I went to go look around the wiring harness connect and moved it and it stalled...! Woohoo, found the problem....Long story short the wiring harness connectory was working itself loose. Started right up and purred like a cat... I did disconnect the wiring connector and there was a little corrision on Pin#6 (pwr) and cleaned that up as well...Starts right up everytime...! I want to thank-you again Don for taking the time to answer my questions, I really appreciate your time and help. I fell in love with my boat all over again...!

As Don said you need to test for current at the ends of each purple wire. I know because I have went through this myself and it was kind of a pain because I ended up removing the whole wiring harness and un wrapping it and testing for continuity then re- wrapping it to eventually find out I had a bad ignition switch but it did give me a better understanding of the electrical system of my rig and I know it's bullet proof for now at least. Just make sure you lube every connection with dialectric grease and tighten and replace all suspect connections.

Thanks. Know what your mean about getting a better understanding of the boat....because I sure have a better one now...Regards,

 

[fat fanny]

Re: 1995 Mercruiser 3.0LX Alpha One - EST Ignition Coil: No 12V

Now that you know the cannon plug was part of the issue load ever pin hole wirh dialectric grease and around the gromet and clamp it back down with a hose clamp to prevent any further corrosion. This should be done every spring and before layup! Your rig like mine is getting to the perishable point all the little things are gonna nickle dime you to death.

 

[fngboater]

Re: 1995 Mercruiser 3.0LX Alpha One - EST Ignition Coil: No 12V

My engine harness connector is doing the same thing. It'll start and run then just die... No power anywhere. I turned the switch for the blower motor on then went back to the engine harness plug, wiggled it and the blower turned on. Sure nuff started right up and ran again. While it was running I went back to the engine wire harness connector wiggled it and it died...no power. Guess ill clean it up and fill it up with die electric grease

 

[Robjr67]

Re: 1995 Mercruiser 3.0LX Alpha One - EST Ignition Coil: No 12V

Now that you know the cannon plug was part of the issue load ever pin hole wirh dialectric grease and around the gromet and clamp it back down with a hose clamp to prevent any further corrosion. This should be done every spring and before layup! Your rig like mine is getting to the perishable point all the little things are gonna nickle dime you to death.

I used contact cleaner and dielectric grease to get it all back in shape. Then took it out and didn't have one issue....Oh, the timing was off too and picked up about 5-6mph.... I had to take it for a little ride...

Here's a phone pic of taking it out for the year...!