Weak Spark Mystery???

[MarkV_Deep6]

Weak Spark


I am rebuilding the ignition system on my 89 V8, and am chasing this problem down. All ignitions components are new down to the champion plugs. All the control wiring is disconnected, and the rectifier has been left disconnected while testing.

• New components tested good with OHM meter. (DVA meter arrived last night.)
• Timer Base
• Stator
• Power Pak
• Coils and plug wires—1 season of use.
• Plug—Champion correct type (don’t remember exact number at the moment)

The spark tester shows a very weak spark on all cylinders with plugs removed (Yes new battery fully charged)

I pulled the flywheel last weekend in preparation to send the Stator to rapair for diag. I noticed the Stator had marks on the coil in one spot that showed wear from the flywheel. I believe this is grounding out my Stator. I wanted confirmation of this from you guys as I have searched the entire board and found nothing on this.

Originally the flywheel needed two magnets re-epoxied, the rest were solid. I have now removed the remaining magnets, cleaned and re-epoxied those also. (Appears this is not the first rework of the flywheel.) The top bearing is not worn , no side play. Not sure why the magnets contacted the Stator; maybe sloppy excessive use of epoxy during a previous fix??

If the weather holds out I hope to put it all together and use the DVA meter this weekend but wanted opinions also.

Thanks.

 

[wavrider]

Re: Weak Spark Mystery???

Sounds like you are gong in the right direction.
If all components ohm out within specs then it may be wiring, connections corroded, insulation frayed or exposed wires causing stray voltage to jump to ground. Chasing electrical problems in an ignition can be hair pulling.

Re ohm all with the dva meter and see what the results are.
You may also try unplugging the main wiring harness to make sure the boat wiring is not drawing anything down, eliminating all wiring except the engine itself.

Hopefuly some of the experts will jump in on this thread.

 

[MarkV_Deep6]

Re: Weak Spark Mystery???

Thanks for the reply, but I have already made sure all the kill wires and any other things that may cause this are eliminated.

I noticed the Stator had marks on the coil in one spot that showed wear from the flywheel. I believe this is grounding out my Stator. I wanted confirmation of this from you guys as I have searched the entire board and found nothing on this.

 

[Lou Eppell]

Re: Weak Spark Mystery???

MarkV...... That engine must crank over at least 300 rpms in order for the flywheel magnets to have that stator create and apply approximately 300 AC volts to the powerpack capacitor. This 300 AC voltage is required in order to have the ignition system engaged.

Check all cables for cleanliness and tightness. Internal cable failure can be pinpointed by hot spots in the cables. I assume you have an excellent battery installed. Does good jumper cables run directly from the battery to the electric starter result in increased cranking speed? If not, and all else above checks out..... possibly a failing starter?

Plugs = Champion QL77JC4 plugs gapped at .040 .

Spark test must be performed with all plugs removed. A tester must have a test gap of 7/16"..... anything less will result in a faulty test.

 

[MarkV_Deep6]

Re: Weak Spark Mystery???

Thanks,
Nothing wrong with crankin RPM's, connections, or starter. Everything is good with the exceptioin of the stator showing evidence of being scraped by a flywheel magnet. If this is not the cause, then its got to be a faulty new stator.
Thought someone may have seen this before.

Red coupler disconnected
All kill wires disconnected
Fast start disconnected
Rectifier disconnected
Very weak spark on all eight with the tester

 

[SuperNova]

Re: Weak Spark Mystery???

Very weak spark on all eight with the tester

What "tester" are you using? And how are you using it? This may be a non-issue. If it is the correct gap-type tester then you either get a spark or you don't...just getting a spark is passing the test.....if it is one of the ones that goes inline with the plug...well, how you use it dictates what it shows--spark strength-wise. You gotta remember--the ignition system is only going to put out the enegy required to make a path to ground--so if you give it an easy path--well, the spark IS going to look weak.

 

[CharlieB]

Re: Weak Spark Mystery???

The spark should be tested with an adjustable gap tester set to 7/16 inch, and should arc brightly blue, orange indicates lowered voltage and will fail under heavy load/WOT.

Flywheel magnets that 'touch' the stator by ANY amount weakens the magnetic field and extremely weakens the voltage/current induced by the moving magnetic field.

Correct your flywheel problem then retest

1. stator voltage using your DVA Meter to ensure the correct voltage output

2. ignition voltage to the coils with the DVA Meter

3. then retest spark quality with a minimum 7/16 gap

Many of these ignitions will throw a bright blue arc well over 1/2 inch, you WILL know it if you get 'bitten'.

 

[MarkV_Deep6]

Re: Weak Spark Mystery???

Ureka!!!!

Thanks Charlie!!! Thats exactly what I needed to know, and verify! U da Man!!

FYI; My spark tester is the nice eight unit tester available from iboats. Costs bout 50.00 or so. Getting any kind of shock is not my idea of fun.

Guess I used TMI in orriginal post. LOL