Killed another coil

[snoski]

I've had various problems with the Mercruiser 260 w/Alpha 1 this season. What I have done so far:
(1) New starter
(2) New starter slave sylenoid
(3) New distributor sensor, rotor, cap
(4) New plugs
(5) Rebuilt the Quadrajet
(6) New fuel pump
(7) New fuel/water separator filter and carb filter
(8) New coil, new coil

The boat will crank and run good maybe 30 seconds and then cuts out.
I am on the 2nd coil and I am pretty sure this one is bad now, because it acts like it loses fire and cuts off. Gas flows good into the carb. so I know it's not a fuel problem.
What would cause 2 new coils go bad?

Thanks

 

[arks]

Re: Killed another coil

What year is the engine?

 

[Don S]

Re: Killed another coil

The boat will crank and run good maybe 30 seconds and then cuts out.

If you have an electric fuel pump, you may have a faulty oil pressure switch. But without a year or SN, who knows.

 

[JustJason]

Re: Killed another coil

bad plug wires.... and incorrect plugs or incorrect plug gap will kill a coil.... to answer your question.

 

[snoski]

Re: Killed another coil

Sorry, it's a 1987 with a mechanical fuel pump.

 

[Bt Doctur]

Re: Killed another coil

the wrong coil will kill the coil, electronic ign. coil with points,or points coil with electronic ign. hi charging output will destroy it too.

 

[drrm123]

Re: Killed another coil

there may also be a ballast resistor on coil or it may need one. it should be white porcelin rectangle shaped part.

 

[Don S]

Re: Killed another coil

there may also be a ballast resistor on coil or it may need one. it should be white porcelin rectangle shaped part.

Mercruiser hasn't used ballast resistors since the early 70' or late 60's, when they went to resistor wires. After '82, they stopped using a points type ignition on the SBC V8 engines and went to elctronic igntion (Thunderbolt Iv).

As stated earlier, bad plug wires, plugs, cap, rotor, anything causing a high resistance, will cause coil failures.

 

[snoski]

Re: Killed another coil

I will check the primary and secondary readings as you mentioned.

 

[Don S]

Re: Killed another coil

I will check the primary and secondary readings as you mentioned.

Looks like you are looking for an easy way out. If the coil has a crack in it somewhere, it won't change the ohm readings one bit. You already know a coil change will fix the problem, what you need to do is find out what causes the coil problem.

 

[waterone1@aol.com]

Re: Killed another coil

I have to ask more questions to give my opinion: How long have you owned this boat ? What was it running like when you first got it ? How many hours have you put on it since you last replaced the coil ? What I'm getting at is 30 seconds is a very short time frame for a coil to go from working to not working. You can rule out external heat to the coil in that 30 second window. A shorted primary or secondary in the coil is highly unlikely unless there is no dielectric left inside the coil. That would take " some doing" especially if this is the second coil. Again, I'm just reading this thread, maybe the other guys have been with you for several threads.

 

[snoski]

Re: Killed another coil

I have owned this boat about 8 years. What I listed in my first post is what I have done to it this year. It started with a bad starter, and after getting stranded on the lake with no fire to the plugs, I decided to do a tune up and found the distributor sensor in bad shape, and things just escallated from there. I went through a troubleshooting schematic that some have posted here and found the coil bad, so I replaced it. I've run the boat at home on muffs and it ran good for a couple of days (I wanted to make sure it was ok before launching it again). Then it started acting up again so I rebuilt the carburator; but it still is not right. It will crank and run maybe 30 seconds and then acts like it loses fire.
I will check the coil this afternoon.
Thanks for all the advise...

 

[drrm123]

Re: Killed another coil

one other thing you can check is to make sure it's wired correctly. pos side should be to battery source and neg side should feed ignition system.

 

[newport dave]

Re: Killed another coil

You may have an ignition module that is not grounded. This is only thing I know of that will kill a T-Bolt IV coil so qiuckly.