switchbox coil questions

[jebeebe]

ob343140 60hp merc 88' running rough at low rpm, runs good at med to high rpm. Cleaned carbs. Someone one mentioned that cranking the enging without the plugs grounded can smoke the coils or switchbox and the motor will still run but with the mentioned symptoms. I had never heard this and was cranking the motor to time it and didn't have the plugs grounded. Any input on this is appreciated...................Jerry

 

[Texasmark]

Re: switchbox coil questions

The comments are true. Having a plug connected to the coil forces the voltage to clamp to the firing potential. If you have no clamp, the voltage (theoretically) can go to infinity.....but doesn't for reasons of the inductor. Since the primary is tied to the secondary by the turns ratio, any excessive (any voltage actually) voltage in the secondary will be transferred to the primary and could over-voltage the trigger transistor, FET or whatever the solid state switch is. Just depends on how high it is and what is the rating of the parts.

Damage on the secondary is wire to wire insulation breakdown, or breakdown of the plastic encapsulation. Once you make the path it just gets worse and the breakdown voltage keeps getting lower and lower.

Sorry.

Mark

 

[Laddies]

Re: switchbox coil questions

Either you or someone needs to ck it with a DVA or you will find parts changing is very expencive and not very productive

 

[Chris1956]

Re: switchbox coil questions

Jerry, If it runs, the switchbox. trigger and coil are good. Running rough at low speed usually indicates a dirty or mis adjusted carb.

 

[jebeebe]

Re: switchbox coil questions

Jerry, If it runs, the switchbox. trigger and coil are good. Running rough at low speed usually indicates a dirty or mis adjusted carb.

I have soaked the carbs overnight and reassembled them and am waiting for a starter drive and carb coupler and then will try them. Hope for the best............Jerry
Thanks for your reply

 

[Chris1956]

Re: switchbox coil questions

Jerry, In that case try to adjust the idle mixture to make it run smooth.

 

[Texasmark]

Re: switchbox coil questions

If we are talking about rough running at idle and not answering the specific coil question, then by no means overlook decarbing with Sea Foam.

Just ressurrected another engine a couple of weeks ago with it. All we did was to put 10 gal of gas in the boat with a whole pint can of sea foam and ran it mostly WOT till the gas was gone. At the beginnning of the process, top speed was 53. At the end of the running we were doing 55. Not bad and it cleared up the hard starting and rough idling.

HTH

Mark