1990 OMC 2.3 L dies once warm

[steve OMC]

I have a 1990 2.3 L OMC cobra. The motor starts up great. Runs smooth. out in the lake for 10 minutes and it starts to miss firs and then just dies. Let it cool and starts again. I have already changed the coil as it was getting hot. I guess my question is what can cause the coil to get so hot it stops working. Also, my Tac was acting very weird. I was saying the RPM was off the board when it was running around 1/2 speed. I am not a mechanic, but I do know when something is over reeving, and it was not.
thanks Much.
Steve

 

[bruceb58]

Hopefully, you still have the ballast resistor in the circuit still. How long have you owned the boat and has it ever run right?

I would disconnect the tach and see how it runs. A bad tach can cause misfire.

When was the last time you changed your points and set the dwell and timing?

 

[steve OMC]

Not sure about the resister, I have not changed anything besides the normal tune up stuff. Timing was set last week. I have had it 3 years and it has run good ever since we did the initial tune up. I did this same thing last year, ran very well till it was good and warm then sputtered and died. replaced the coil and it was good. The mechanic told me then the coil should really be standing up straight not laying on its side as designed. he actually told me to keep one on board and to expect this to be ongoing with the coil. this is why I put one in as soon as it started happening aging this year.
I am going to try to get it to do it in the driveway and check for spark once it dies. anything else to check?

 

[bruceb58]

Angle of the coil does not matter.

When did you last change the points?

Remove the tach and try.

 

[steve OMC]

Points, condenser, new distributer cap and rotor all mid season last year. I will try the Tach removal tonight when I get home. Thanks, I will let you know
Steve

 

[bruceb58]

Do you set your dwell with a dwell meter? Having the dwell set too high(too small of a gap) will cause your coil to run hotter than normal.

 

[steve OMC]

It was set with a dwell meter, But we will re-check that as a possibility as well.

 

[steve OMC]

lets say something WAS causing the coil to over heat.. will that stop it from producing spark?

thanks

 

[bruceb58]

There are only a couple ways a coil will overheat.

1. Your dwell is too long
2. You don't have a resistor wire or ballast resistor

1st one is easy to check and it sounds like you are going to do that. The second is also easy to check. Rotate the engine so that the points are closed and measure the voltage on the positive side of the coil to ground. If it is between 7 and 9 volts you are good. If it is 12V you don't have a ballast or resistor wire in your system.

 

[steve OMC]

I hope this is the end to this post

I had the maintenance manager from work come to my place and we put the motor on muffs. Ran it for 10 minutes till the thermostat opened and sure enough 3 minutes later,, spit, sputtered and died. We looked at this and we looked at that, checked all the things you noted above... everything was good.

we opened up the distributor and one of the tabs on the top of the rotor that hold the strip of copper in place was missing and the copper was sideways. :-(

Hence the reason for the super hot coil!

was trying to produce enough spark to jump across the gap at that point as well as on the plugs.
ran it in the drive way for 20 minutes at around 3 k all was good!!

Will come back once we get her in the water and let you know for sure.
Thanks for your help old man!!

have a great day on the water "p)"

Steve

 

[bruceb58]

Well that's good!

So it was the tune up parts you did last year then! What brand were they?

Thanks for your help old man!!

Hey!!! :faint: