Author Topic: Diagnosing the 3.7L Ignition Issue. (Read 33829 times)

dorelse · « **on:** April 16, 2016, 07:09:18 PM »

Ok, with the engine now all wired up, on its new stand, new battery, wired up properly, etc...I started digging into what's going on with the no spark issue.

As far as I can tell...with the points open, the tester light lights up when attached to the negative side of the coil and I ground out the tip. (Shown in the video). With it closed, and the tester light on the (+) side of the coil and grounded out, it lights up.

I think that part is all good. The problem is from the cap to the plugs...whatever that could be?

http://youtu.be/oOUKmBjet2c

Terry_Curran · « **Reply #1 on:** April 16, 2016, 09:27:30 PM »

I'm getting 404 not found?

dorelse · « **Reply #2 on:** April 16, 2016, 09:33:09 PM »

Quote from: SSV-191 on April 16, 2016, 09:27:30 PM

I'm getting 404 not found?

Of course it shows for me since its my account...

Link:

https://www.youtube.com/watch?v=oOUKmBjet2c

Terry_Curran · « **Reply #3 on:** April 16, 2016, 09:35:32 PM »

Now it says, no longer available.

Terry_Curran · « **Reply #4 on:** April 16, 2016, 09:37:57 PM »

Have you tried your spark tester on your coil wire and turned the motor over? Maybe the windings in the coil are bad and not sending voltage to the distributor?

Terry_Curran · « **Reply #5 on:** April 16, 2016, 09:39:37 PM »

Link works now.

dorelse · « **Reply #6 on:** April 16, 2016, 09:48:10 PM »

Quote from: SSV-191 on April 16, 2016, 09:37:57 PM

Have you tried your spark tester on your coil wire and turned the motor over? Maybe the windings in the coil are bad and not sending voltage to the distributor?

Brand new coil...and yeah, I did, I never saw that light up.

Terry_Curran · « **Reply #7 on:** April 16, 2016, 09:59:26 PM »

Are the points opening? Is the gap correct?

dorelse · « **Reply #8 on:** April 16, 2016, 10:10:30 PM »

Quote from: SSV-191 on April 16, 2016, 09:59:26 PM

Are the points opening? Is the gap correct?

Yep, that video is when I manually turned the engine over to open the contact breaker, so that cam lobe is working. Not sure on the gap.

Terry_Curran · « **Reply #9 on:** April 17, 2016, 07:32:57 AM »

Here's a link telling you how to troubleshoot a breaker point ignition.

http://www.gasenginemagazine.com/gas-engines/understanding-breaker-point-ignition-systems.aspx

Rich_V174SS · « **Reply #10 on:** April 17, 2016, 08:03:26 AM »

With the tester connected to the negative side of the coil the light should flicker on & off with the opening and closing of the points as you crank the engine. Put a spark plug onto one of the plug wires and let the plug ground against the engine and see if you get sparks at the tip when you crank the engine.

dorelse · « **Reply #11 on:** April 17, 2016, 04:14:45 PM »

I'm using one of those spark plug tester lights to see if spark is getting to the plugs. I'm not seeing it light up. I've even tried putting it in between the coil & distributor wire and also never seen it light up. So something isn't completing the circuit when that contact breaker opens.

Here's the tester light hooked up to the (+) side of the coil, with my grounding it to the alternator bracket (and my helper):

https://www.youtube.com/watch?v=zLrfeittVmg

(-) Side of the coil...grounded to the Alt bracket

https://www.youtube.com/watch?v=CKCL6gQ1jgQ

dorelse · « **Reply #12 on:** April 17, 2016, 04:18:30 PM »

Granted I'm new at this...but I would have expected that when the clip is attached to the (-) side and then I ground the test light, that it would only light when the contact breaker was open right?

Rich_V174SS · « **Reply #13 on:** April 17, 2016, 04:19:14 PM »

When on the negative side of the coil the test light should go on & off. So the points are not making good contact. I would first try polishing the contact surfaces of the points to see if that helps.

dorelse · « **Reply #14 on:** April 17, 2016, 06:21:46 PM »

The distributor cap looks pretty corroded on the inside...I was going to just order a new one...$12 seems like cheap insurance.

Rich_V174SS · « **Reply #15 on:** April 17, 2016, 06:34:39 PM »

Quote from: dorelse on April 17, 2016, 04:18:30 PM

Granted I'm new at this...but I would have expected that when the clip is attached to the (-) side and then I ground the test light, that it would only light when the contact breaker was open right?

Yes, which leads me to believe they aren't making good contact when closed, the light stays lit.

Changing the cap will help with spark transference to the plugs but first you need to make sure it generates spark.

dorelse · « **Reply #16 on:** April 18, 2016, 10:24:07 PM »

Looked over everything again...used a little sandpaper to clean the contact breaker. I then busted out the dremel & brass wire brush and cleaned all the points and center point?

The thing I found interesting is (and I might be wrong) but is the center point plastic with an outer ring of brass? I couldn't quite tell what was metal vs. plastic there. When I used the wire brush, the ring around the plastic point, cleaned up to a nice brass shine. Before it was black...so think that might have been the problem.

After cleaning it all up, I now have spark!

https://youtu.be/Q2OSsfKfXOg

dorelse · « **Reply #17 on:** April 18, 2016, 10:27:34 PM »

Ah..that's a carbon 'button' in the center...ok...got it. I'm quite certain that the combination of dirty points on the cap, and that carbon button were preventing good current flow. I would think the new cap would be the correct fix.

Rich_V174SS · « **Reply #18 on:** April 18, 2016, 10:28:28 PM »

Cool that you got spark! Not you just gotta get that thing to crank faster.

dorelse · « **Reply #19 on:** April 18, 2016, 11:03:38 PM »

Quote from: Rich_V174SS on April 18, 2016, 10:28:28 PM

Cool that you got spark! Not you just gotta get that thing to crank faster.

Yeah...it would appear that the starter is toast. I was planning to just get this one rebuilt...unless you think the ebay high torque one's would be better? Would require some wiring changing I think to that additional solenoid...

http://www.ebay.com/itm/NEW-STARTER-Model-270-3-7L-325-390-470-488-MERCRUISER-STERN-DRIVE-1969-1989-/130923916316?hash=item1e7bac6c1c:g:1OwAAOSw9r1WCWlc&vxp=mtr