mercruiser no spark

[wildcat8466]

I have mercruiser 3.0 have no spark at plug, I checked all voltage at + coil and - coil got 12 volts and even have 12 volts at points with ignition on but no spark at plug, new points and condencer and rotor button what can I do next!!!!

 

[Don S]

Re: mercruiser no spark

Is the point gap correct?
Did you check the coil wire (one from cap to coil)
What shape is the distributor cap itself in? especially the button in the center that rides on the rotor.

 

[wildcat8466]

Re: mercruiser no spark

Yes it is at .022 like it says and yes there was voltage at the end of the coil wire to. the cap looks in decent shape and the buton is new. was running just last week. now no spark very confused!!

 

[wildcat8466]

Re: mercruiser no spark

I am totally braindead can someone just type a list of what to check and the steps you would take to diagnose my problem of no spark at plug

 

[Haut Medoc]

Re: mercruiser no spark

Have you changed the cap & rotor?......​

 

[Zim]

Re: mercruiser no spark

Could be the rotor under the cap is worn, not spinning, and not passing the current along. Might check that.

 

[wildcat8466]

Re: mercruiser no spark

have replaced the points ,condencer and rotor button. the button does spin and seems ok

 

[Zim]

Re: mercruiser no spark

plug wires?

 

[wildcat8466]

Re: mercruiser no spark

have not replaced plug wires but it was running last week and now it will not produce a spark at the plug. I have 12 volts at the + side of coil and the - side of coil with the key on. there is voltage at the points and when i ran a screwdriver around the points, it would produce a spark every now and then. I took the coil wire off of rotor cap and it had 12 volts there.I do not have a dwell meter and the .022 that the points are set at is very close and I could only tell that it was working in the dark. would the dwell cause it to not put a spark at the plug????

 

[freddyray21]

Re: mercruiser no spark

condensers are known to be bad new out of the box. The points should produce an arc every time they are opened and close. Not every once in a while. Check to see if you have a shorted set of points. From the points wire to ground there should be a direct short with them close and no continuity when open. A shorted set of points won't fire. Did you tune it up and now you don't have a spark? If so put the old parts back in and see if you have a spark. If it ran with old parts and not with new then you have a bad part

 

[Don S]

Re: mercruiser no spark

I do not have a dwell meter and the .022 that the points are set at is very close and I could only tell that it was working in the dark.

Did you have the points on the highest part of the distributor cam lobe when you set them at .022?
Was the feeler gauge perfectly clean? I watched a guy set his points one day with an oily feeler gauge. There cannot be any oil on the points.

 

[wildcat8466]

Re: mercruiser no spark

I did set the points on the highest point and set the points with a clean feeler guage. So does that mean that the dwell is properly set?????

 

[Don S]

Re: mercruiser no spark

So does that mean that the dwell is properly set?????

No, that just means the points are gapped to where it should run so you can actually check the dwell. The dwell is the final test. Then, you have to reset the timing and readjust the carb mixture and idle speed.

 

[wildcat8466]

Re: mercruiser no spark

ok I will worry about the dwell when I can get it spark properly any other thing that I can check?

 

[Coors]

Re: mercruiser no spark

have not replaced plug wires but it was running last week and now it will not produce a spark at the plug. I have 12 volts at the + side of coil and the - side of coil with the key on. there is voltage at the points and when i ran a screwdriver around the points, it would produce a spark every now and then. I took the coil wire off of rotor cap and it had 12 volts there.I do not have a dwell meter and the .022 that the points are set at is very close and I could only tell that it was working in the dark. would the dwell cause it to not put a spark at the plug????

I don't understand; a coil wire has 12 volts? Is this the plug wire sized wire from the coil to the center of the distributer?

 

[wildcat8466]

Re: mercruiser no spark

from the wire of the points to ground I have 5 ohms and the points are open and the coil wire is still hooked up. do you test the ohms with coil wire still hooked up if so I"m grounding out. How could this happen?????

 

[wildcat8466]

Re: mercruiser no spark

yes that isthe center coil wire at the end where it hooks up to the cap has 12 volts

 

[Bondo]

Re: mercruiser no spark

yes that isthe center coil wire at the end where it hooks up to the cap has 12 volts

That should be 20,000Volts or More........

If you supply 12V to the (+) side of the Coil,......
And touch a Ground to the (-) side of the Coil,.......
You Should get a Spark of 20,000V or More from the Coil Tower Wire(aka. the Big Center Wire)......

 

[Coors]

Re: mercruiser no spark

Yeah, 20000+ volts; I'm getting lost on that one.

 

[Don S]

Re: mercruiser no spark

How are you measuring the voltage to get 12V out of the center coil tower?
If you are measuring from coil tower to ground and getting 12 Volts, then the primary and secondary windings are shorted internally. You need a new coil.