4.3 Mercruiser ignition coil problem

[Dean8]

I have a 2000 4.3 Mercruiser. The ignition coil was sparking from one terminals to the center so I replaced it with a new one. I started the engine with no problems so off to the water I go. I started it and went about 150 feet and it died. I went back to the dealership and ordered another ignition coild thinking I had a faulty coil out of the box.
I received my second new one and installed it and started it at the house and let it idle for 15 minutes and had no issues. I reved it a little and had no issues so off to the lake I go. Once again I got out 150 and it died again. This time I brought my origional coil with me and I replaced it on the spot and it fired up (with the sparking still occuring) but I was able to run it with no problems.
Can you please help me understand why two new ignition coils went bad but the OEM still works?
Thank you for your time.

 

[hooks1]

Re: 4.3 Mercruiser ignition coil problem

First thought is that it is the high tension coil wire is faulty and causes the sparking and the new coils were too wimpy to stand up to it and burned out. I don't have a second thought but I would replace the coil wire and evaluate the age and condition of the plug wires and plugs before doing anything else. The sparking was the coil trying to find the shortest path to ground which should be the spark plug gap - I would guess the spark plugs are old and the elecrodes are worn down.

 

[Dean8]

Re: 4.3 Mercruiser ignition coil problem

Thank you for your time. I will look into this.

 

[wire2]

Re: 4.3 Mercruiser ignition coil problem

Check the wires with an ohmmeter. They should read ~1000 ohms per inch of length.
It sounds like one or more of yours have burned the carbon wire back from the brass end. That results in very high voltage from the coil, which will arc over in odd places.

 

[ezzymonie]

Re: 4.3 Mercruiser ignition coil problem

i have the same problem with my 1989 4.3 lx v-6 205 hp thunderbolt ignition changed coil and wire still does the same thing going to check all gound wires coming from coil let me know if you have solved the problem

 

[Dean8]

Re: 4.3 Mercruiser ignition coil problem

After going through two ignition coils from the marina I went to Auto Value parts store and they helped me out with a ignition coil and spark plugs. The coil from the marina costs $60 and the coil from the parts store cost me $20. So I replaced all of the plugs and the coil and I went to the lake today and it ran great all day. I'm going to be replacing the wires in the near future when I find the correct ones from the parts store.

 

[Don S]

Re: 4.3 Mercruiser ignition coil problem

You may have had a bad spark plug that wasn't firing. That will crack the coil tower in short order. Had you replaced the plugs sooner, you wouldn't have lost the other coils.