3.7 Ignition/Stator

[elahuta]

Hi Everyone! I have Mercruiser I/O 3.7, 4 banger that I love. But, I am not getting any spark to the plugs. I have juice to the coil on the + side but no juice/spark comming out of the coil or coil wire. I replaced the coil and the same thing. I was thinking it could be the stator but I do not know how to test it. I had a friend crank the motor and I took a test light to the two wires that come out of the stator and nothing.

I just don't understand...

How do I test the stator?
If the coil is getting power on + side why doesn't it send a spark out of it?

Please Help!!!!!!

Thanks,

Ed

 

[s1120]

Re: 3.7 Ignition/Stator

If you got power going to the coil, I dont see how it could be the stator. Sounds like bad points to me.

 

[Don S]

Re: 3.7 Ignition/Stator

Put in some new points and condenser.
The stator is for charging only, it's not an outboard.

 

[rodbolt]

Re: 3.7 Ignition/Stator

you may also wish to check the continuity between the point plate in the distributer and actual engine ground.
the 3.7 tended to lose it occasionally.

 

[elahuta]

Re: 3.7 Ignition/Stator

Thank you guys.
But I still do not understand why replacing the points would do anything.
I turn the key the motor cranks and I have no power out of the coil wire. Just to prove it I stuck a test light on the coil and stuck my finger in coil (Very Bad) and nothing.
If the coil does not produce any power to the cap, rotor and points. How would replacing the points solve the problem.

Thanks,

Ed

 

[stonyloam]

Re: 3.7 Ignition/Stator

OK lets see if I can remember my theory. The points are opened and closed by a cam on the distributor. When the points close current flows into the primary of the coil creating a magnetic field (few windings). when the points open the current stops and the field collapses. When the field collapses it induces a voltage in the secondary coil (lots and lots of windings). This gives you your ignition spark. So if the points are bad (no contact) you will never see a spark because you never get current to the coil. If the points are shorted you would never get a spark because the magnetic field never collapses. The condenser acts kind of like a buffer to increase point life (I think). This is how you get from 12 volts to 40,000 volts.

 

[stonyloam]

Re: 3.7 Ignition/Stator

Just reread your post, you got it backwards. The points provide power to the coil, not the other way around.

 

[stonyloam]

Re: 3.7 Ignition/Stator

Here is how it works: when the distributor rotates it does two things, it rotates the cam under the little arm of the points and it lines the rotor up with one of the terminals of the distributor cap. It goes like this, when the lobe of the cam rotates under the point arm it opens the points this causes the coil to spark, the spark travel through the insulated spark wire of the coil into the center of the distributor cap, down through the cap through the contact into the rotor which is lined up with one of the spark plug terminals. The spark jumps the gap into the terminal, through the plug wire and into the spark plug.

If the points are good, with the ignition on (make sure you have voltage to the points), cap off and points closed, you should be able to generate a coil spark by opening and closing the points (use something non conducting). NOT your finger!! If your points are NOT opening (stuck together, or arm worn to the point that it does not contact cam or base loose) you will see voltage at coil but no spark.

Good luck

 

[Don S]

Re: 3.7 Ignition/Stator

Read this, it explains how the points type ignition works and how to set it up.

http://autorepair.about.com/cs/generalinfo/a/aa052502a.htm

 

[CheapboatKev]

Re: 3.7 Ignition/Stator

Thank you guys.
But I still do not understand why replacing the points would do anything.
I turn the key the motor cranks and I have no power out of the coil wire. Just to prove it I stuck a test light on the coil and stuck my finger in coil (Very Bad) and nothing.
If the coil does not produce any power to the cap, rotor and points. How would replacing the points solve the problem.

Thanks,

Ed

Are you kidding me???? Geeez...that coulda went straight to UTUBE if you suddenly got your spark...I cant find the "finger in the coil" field test anywhere in my books...

 

[elahuta]

Re: 3.7 Ignition/Stator

I wanted to say Thank You to everyone who took the time to read and help me out.
It is nice to know a brotherhood/family of a people among boating.
I don't know how I can help I boats forum but, if there is please let me know!!.

Thanks,

Ed