mercruiser 120 no spark

[weightset]

Re: mercruiser 120 no spark

well when i first set the voltmeter on the coil today i started at 11.2 until i started to crank then i only ended up with the 4.2v what do you think would have caused that, and if you were in my shoes where would you start at to get spark

 

[Don S]

Re: mercruiser 120 no spark

Weak battery, loose, corroded, failing battery cable connection. You name it. You can't get 2 tests to match or come close to the same, so it leaves your testing methods in question.

 

[weightset]

Re: mercruiser 120 no spark

Well i got the boat running was a bad coil as i first thought. But now i cant keep it running unless have a small amount of throttle on

 

[NetDoc]

Re: mercruiser 120 no spark

With that low of voltage, it sounds like you have a ballast resistor and one that is failing at that. If not a ballast resistor, then the Oil Pressure cut off switch could be the issue.

I agree with Don though: change points and condensor, set the gap (dwell) and go from there.

 

[dubs283]

Re: mercruiser 120 no spark

If not a ballast resistor, then the Oil Pressure cut off switch could be the issue

huh??

never heard of an oil pressure cut off switch on any mercruiser product

there is an oil pressure switch for the alarm system on some models

and an oil pressure switch on carb engines with electric fuel pumps

but neither of those two systems has anything to do with the ignition system