3.7 showing me no love. I think the spark has left our relationship

[frankttaylor]

All,

OK so the boat ran great last summer. I replaced wires, plugs, points, condenser, cab and rotor. I winterized it per the owners manual and upon starting for the new season it just will not fire. I am getting plenty of fuel but there is no spark at the points. The points look essentially new so I doubt that is the problem. I had the coil tested and he said without the actual specs it was hard to say if it is bad or not. I have have 12 volts to the coil and the ground is good. I am not thrilled at throwing 50 bucks at a coil if that isn't the problem. Thoughts?

1990 Blue Water
3.7L Mercruiser

Thanks,

Frank
:blue:

 

[Bondo]

Re: 3.7 showing me no love. I think the spark has left our relationship

Ayuh,... Is there voltage to the points when they're open,..??

Is the other side of the points properly grounded,..??

If so, change the points...

It's the function of the points, to fire the coil...

 

[frankttaylor]

Re: 3.7 showing me no love. I think the spark has left our relationship

OK I guess I need to take an internal combustion 101 class. How do I check the voltage at the points and the ground? Thanks for your help!

 

[Oshkosh1]

Re: 3.7 showing me no love. I think the spark has left our relationship

If it ran prior to the new ignition components I HIGHLY doubt the coil just "went" by itself in a static state.
I'm sure it's just a matter of a connection somewhere to chase down.
A DVOM will be crucial in finding the weak link here.

Just not sure about the wording of the post...you say that you "replaced" the points, then say they look "essentially new". You bought old points???

They're probably $7 new.

Make sure the point gap is set, then confirm the dwell with a meter. Check static and running when you time it.

 

[frankttaylor]

Re: 3.7 showing me no love. I think the spark has left our relationship

I bought new points last summer. Ran the boat a few times o when I say essentially new that is they are not "brand new"" any longer. Sorry for the confusion. I do have a meter. We did check the gap also. We should be able to see spark through the points when the engine is being cranked and the cap and rotor are removed correct?

 

[Bondo]

Re: 3.7 showing me no love. I think the spark has left our relationship

I bought new points last summer. Ran the boat a few times o when I say essentially new that is they are not "brand new"" any longer. Sorry for the confusion. I do have a meter. We did check the gap also. We should be able to see spark through the points when the engine is being cranked and the cap and rotor are removed correct?

Ayuh,... dependin' on the level of lighting...

points tend to glaze over, from Non-use... Change 'em...

 

[frankttaylor]

Re: 3.7 showing me no love. I think the spark has left our relationship

Should I change the condenser also?

 

[Oshkosh1]

Re: 3.7 showing me no love. I think the spark has left our relationship

We should be able to see spark through the points when the engine is being cranked and the cap and rotor are removed correct?

Yes...you'll also hear the "snap"...

Take a piece of cardboard and run it through the gap to clean off the new points. I did this to a 40 y/o snowmobile that was only firing on one cylinder with the original points sitting in a barn since 1988. They were a PITA to replace(unlike auto/marine) so I started with "cleaning" them. STILL running fine!

I can't see them corroding in that short of time unless they were in a very moist enviroment.

 

[Oshkosh1]

Re: 3.7 showing me no love. I think the spark has left our relationship

Should I change the condenser also?

If no result from cleaning them and you still feel your new points have glazed over in such a short time, AND feel the need to buy new(again), then yes, get both...just to be sure.

 

[frankttaylor]

Re: 3.7 showing me no love. I think the spark has left our relationship

Well I used a couple of those moisture removal "pots" but still had a lot iof mildew and the hoses on the motor have mold or mildew on them. Maybe there is moisture in there to corrode although there didn't seem to be a any evidence of moisture in the cap.

 

[Oshkosh1]

Re: 3.7 showing me no love. I think the spark has left our relationship

That's what I consider "very" moist!
Still...try the cardboard to clean them off. If it works, great...you can decide whether they are bad enough to replace. If not, get new and give them a shot. It may just be a little soft build up on the contact point.

 

[Oshkosh1]

Re: 3.7 showing me no love. I think the spark has left our relationship

Lol!
Saw your location...You're on the west side of the Cascades...home of the infamous "black mold". I was stationed in the Puget Sound area for a decade and know how wet the winters are, so corrosion is more a probability than possibility!

 

[stonyloam]

Re: 3.7 showing me no love. I think the spark has left our relationship

OK I guess I need to take an internal combustion 101 class. How do I check the voltage at the points and the ground? Thanks for your help!

Here you go LOL: The coil is simply a transformer that steps up voltage from low (12V) to high (20,000V). Here is how it works: A (step up) transformer has two coils, a primary with few windings and a secondary with many windings. With the ignition on voltage (12) is applied to the coil + . When the points close current flows through the primary to ground (from the coil-) through the closed points and builds up a electromagnetic field. When the points open the current stops and the field collapses and generates a voltage in the secondary windings. Because the secondary winding has many many more turns in the winding the voltage that is generated is much higher. That secondary winding is connected to the center coil wire, and the voltage is transmitted to the center of the distributor cap, flows down into the rotor and jumps across to whichever sparkplug wire it is pointing to at the time, through the wire to the plug and jumps the plug gap (sparks) to ground. So you can test your points and coil by removing the cap and rotor, remove the center wire from the cap and place it close (1/4 inch or so) from bare metal on the block, put a piece of insulating material between the points, turn on the ignition and with a short piece of insulated wire quickly jumper from one side of the points to the other. You should get a spark from the coil wire every time you REMOVE the wire. If you do, your coil is good and your points are bad. Change them. As for the condenser, cange it if you like. Good luck.

 

[bfjou812]

Re: 3.7 showing me no love. I think the spark has left our relationship

There should be a resistance wire that runs from the choke to the coil. Check that ,if it is bad the coil will not get the correct voltage. I've had this happen twice to me and am considering replacing it with a ballast resistor.

 

[FreeBeeTony]

Re: 3.7 showing me no love. I think the spark has left our relationship

Here you go LOL: The coil is simply a transformer that steps up voltage from low (12V) to high (20,000V). Here is how it works: A (step up) transformer has two coils, a primary with few windings and a secondary with many windings. With the ignition on voltage (12) is applied to the coil + . When the points close current flows through the primary to ground (from the coil-) through the closed points and builds up a electromagnetic field. When the points open the current stops and the field collapses and generates a voltage in the secondary windings. Because the secondary winding has many many more turns in the winding the voltage that is generated is much higher. That secondary winding is connected to the center coil wire, and the voltage is transmitted to the center of the distributor cap, flows down into the rotor and jumps across to whichever sparkplug wire it is pointing to at the time, through the wire to the plug and jumps the plug gap (sparks) to ground. So you can test your points and coil by removing the cap and rotor, remove the center wire from the cap and place it close (1/4 inch or so) from bare metal on the block, put a piece of insulating material between the points, turn on the ignition and with a short piece of insulated wire quickly jumper from one side of the points to the other. You should get a spark from the coil wire every time you REMOVE the wire. If you do, your coil is good and your points are bad. Change them. As for the condenser, cange it if you like. Good luck.

EXCELLENT explaination!!

 

[frankttaylor]

Re: 3.7 showing me no love. I think the spark has left our relationship

Carboard trick worked great! Runs like a top. Thanks again!

 

[$300boat]

Re: 3.7 showing me no love. I think the spark has left our relationship

Here you go LOL: The coil is simply a transformer that steps up voltage from low (12V) to high (20,000V). Here is how it works: A (step up) transformer has two coils, a primary with few windings and a secondary with many windings. With the ignition on voltage (12) is applied to the coil + . When the points close current flows through the primary to ground (from the coil-) through the closed points and builds up a electromagnetic field. When the points open the current stops and the field collapses and generates a voltage in the secondary windings. Because the secondary winding has many many more turns in the winding the voltage that is generated is much higher. That secondary winding is connected to the center coil wire, and the voltage is transmitted to the center of the distributor cap, flows down into the rotor and jumps across to whichever sparkplug wire it is pointing to at the time, through the wire to the plug and jumps the plug gap (sparks) to ground. So you can test your points and coil by removing the cap and rotor, remove the center wire from the cap and place it close (1/4 inch or so) from bare metal on the block, put a piece of insulating material between the points, turn on the ignition and with a short piece of insulated wire quickly jumper from one side of the points to the other. You should get a spark from the coil wire every time you REMOVE the wire. If you do, your coil is good and your points are bad. Change them. As for the condenser, cange it if you like. Good luck.

I'm assuming, that if I did this and did not get a spark, the coil is bad?

 

[stonyloam]

Re: 3.7 showing me no love. I think the spark has left our relationship

Chances are that is the case.

 

[$300boat]

Re: 3.7 showing me no love. I think the spark has left our relationship

Chances are that is the case.

Thanks. Any tricks for checking the coil?

 

[Eric 3.7LX Alpha 1]

Re: 3.7 showing me no love. I think the spark has left our relationship

Absolutely....

You test the coil by using a Digital multimeter set on resistance/Ohms and disconnect wires off the coil.

The primary resistance is 1.1 - 1.5 Ohms
The secondary resistance is 9,400 - 11,700 Ohms

if it is not within those numbers it is NG.

See the link on testing a coil:
Coil Test - Testing Your Ignition Coil - Coil Resistance Test - How To Test Your Ignition Coil With an Ohmeter