Author Topic: No spark sometimes  (Read 11137 times)

Gene

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No spark sometimes
« on: September 04, 2012, 09:53:43 PM »
Hi.  My name is Gene.  I've been reading the forum for a while and have gained much helpful knowledge about my FL350, so I know there are some really experienced Odyssey mechanics amongst us.  Now I have a strange problem that I hope someone can help me with.

I have spark when the plug is laying on top of the cylinder, but I have no spark when a plug is in the cylinder.  I read on this forum about the problem with a worn starter sucking too much juice, but the problem is still there when I use the pull starter.

I have had the Odyssey for a number of years. It is totally stock.  I went through two top ends. After burning the second piston (due to an unnoticed crack in the manifold) I acquired a second engine on ebay that has been running well for the last couple years.  This summer I had the Salisbury clutch blow up.  Thankfully no one was hurt.  The belt guard was destroyed but it contained all the flying metal. The engine still ran so I found a Comet 102c clutch only to discover the new clutch was wobbling at least a half inch at the bolt. The output side of the crank was seriously bent in the explosion.  I transferred the top end from that engine to the bottom end from my burned engine that I had never got around to rebuilding.  I also transferred the stator and starter and the intake and exhaust because I only have one each.  The result probably needs new rings (105 psi on my old compression tester) but I figured enough to get me through the rest of summer.   I cleaned all the connectors and the battery was new last fall.  There were a lot of pieces flying under the belt guard but the only damage I could find was the ground that hooks up to the front belt guard bolt was knocked off, so I replaced that.  If I had lost a whole wire I expect I would have no spark at all, but the spark seems fine as long as no plug is in the cylinder.  As soon as I screw in a plug in even partway my spark is gone.

LiveWire

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Re: No spark sometimes
« Reply #1 on: September 05, 2012, 07:19:02 AM »
I spoke with Gene on the phone last night and suggested he post here for additional input. I have never seen or read about a situation where using the pull starter, you would get spark with the plug out, but not with a plug in the cylinder and another in the wire laying on the head. My thoughts are that the spark is weak. Without a plug in the cylinder, maybe it spins over fast enough to make it spark. The other thing I wonder about is if there is play in the bottom end that when under load from compression, moves the rotor out of alignment with the pickup coil.

I suggested checking the resistance of the coil and cutting 1/4" off the spark plug wire an reinstall the cap. Any one else have suggestions?

odypilots

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Re: No spark sometimes
« Reply #2 on: September 05, 2012, 09:10:20 AM »
You hit on the suggestion that came to mind as I read his post, that of a weak spark. It seems the answer in the other instance was a new battery. I know it would suck to buy another battery to find that wasn't the problem. Gene, have you had the battery tested?

IS the engine getting fuel? I'd double check all the connections, wiring, fuel pump hoses, carb connections, etc.
The usual 'my two cents' disclaimer applies. :)

Factory 45

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Re: No spark sometimes
« Reply #3 on: September 05, 2012, 10:22:28 AM »
Hi guys...I just started looking at this problem and the 350's spark system. Its as simple as it gets. BATTERY HAS NOTHING TO DO WITH SPARK OR CDI. It will only effect cranking revolutions and the engine speed thereof.

If you dont have the book...download it. Get familiar with the system and symbols...you will need a good multimeter. Test the components electrically (coil,pulse generator, exciter/stator) before you tear anything apart. Specs are in section 14.

Simple overview...pulse generator gets an ac signal...sends it to the CDI. CDI then pumps up the ac signal and discharges higher signal to the coil. In other words weak signal equals weak spark.

My first thought is that the pulsing coil could have gotten damaged or rubbed when your crank/clutch failure occoured. It may be worth it (after testing) to remove the pullstart cover, case on that side and do a visual inspection of your previous work...and to check for the oil issue. If the pulsing coil is partially shorted to ground it could be found by using a multimeter. If the pulse coil (when totally unplugged) shows any resistance AT ALL to case ground...on either wire it would weaken the spark. DONT PULL THE FLYWHEEL until you test the pulsing coil...just because you may need to rotate the engine some to ensure the flywheel isnt rubbing the wiring at ALL 360 degrees of engine rotation.

The other silly...but important issue could very well be the system ground. Looking at the wiring diagram the coil, CDI, and pulse generator use the same ground. Check them...and get back.

The only other thing could be (other than an ignition component failure) is a bad ac power source to the CDI from the stator. (black/red wire is the exciter coil which a stand alone ac leg that just powers the CDI)
« Last Edit: September 05, 2012, 10:38:25 AM by Factory 45 »

Gene

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Re: No spark sometimes
« Reply #4 on: September 05, 2012, 07:56:41 PM »
Thanks for giving this some thought.  I didn't have a lot of time tonight but I got out the multimeter and my coil looks good:  0.2 ohm on primary, 4.2 K ohm on secondary. I nipped the end off the plug wire while I had the boot off.  I have 116 ohm on the exciter wire to ground, and 116 ohm between the two wires on the pulse generator.  I have 0.1 ohm between the green ground in the cdi plug to the cylinder head so I think my system ground is still good at least to the cdi.  I will tackle the cdi this weekend.

The spark might be weak but it looks like it always did when it was running.  I never thought the spark was particularly robust to begin with.  My friend Fred suggested I increase the spark plug gap to 40 or 50 thousands as this has worked for him to fire engines with low compression and the spark will jump that gap with the plug out of the cylinder.
 

LiveWire

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Re: No spark sometimes
« Reply #5 on: September 06, 2012, 07:05:45 AM »
The crank that went bad likely did not simply bend between the weight and the end of the crank. It may have done that too, but likely the crank spun on the pin. That means the other end of the crank would also go out of whack and rub like Factory45 suggested.

Factory 45

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Re: No spark sometimes
« Reply #6 on: September 06, 2012, 02:02:44 PM »
Ya...wow if it turns out that simple...just tell the electro geeks to back down. lol

Looks like all your numbers are spec for sure. Try doing a few tests outside the box. Unplug the stator AC leads for the charging system and test between each yellow and the Bl/Red...to be sure the stator isnt shorted to the exciter coil. Each test should indicate NO Circuit. If a resistance value appears at all during this test...there is a problem on the stator plate. But with correct values from JUST the exciter...It doesnt seem that may be an issue.

Back to the trigger and clutch failure just for a second...did the trigger perhaps get hit AWAY from the flywheel when the clutch failed? (crank twisted) Too large of a gap between the trigger and flywheel could result in weak trigger activity. (with correct resistance values)

You probably were not prompted to look...but by chance did you see any rubs or scuffs on the flywheel or stator coils when you changed it over?
« Last Edit: September 06, 2012, 03:06:35 PM by Factory 45 »

Gene

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Re: No spark sometimes
« Reply #7 on: September 06, 2012, 06:32:02 PM »
I threw the old block with the bent crank on my bench and was trying to set up the dial indicator to see if the flywheel side of the crank is bent and turns out I didn't need the dial indicator, I could see a serious wobble on the flywheel side.  I guess this weekend I will pull the gas tank and the covers and see how bent my stator plate is.  A quick glance at the book didn't reveal how much clearance I should have between the flywheel and the pulse generator.

LiveWire

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Re: No spark sometimes
« Reply #8 on: September 07, 2012, 07:07:10 AM »
Maybe you will get lucky and will be able to see marks on the stator plate where the pickup was shoved over. The reason there are no specs in the book is you're not supposed to take that apart. It can only adjust within the range of the holes. You could just adjust as close as possible within the holes, but before hitting the rotor.

Factory 45

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Re: No spark sometimes
« Reply #9 on: September 07, 2012, 04:25:47 PM »
I just put one together...I could pop a cover and measure the trigger air gap.(just for the sake of establishing a good comparison for you) The trigger sits on a little tin/flimsey bracket that bends very easily.(pretty sure on that...not positive...remember it for sure is replacable individually) Livewire is right though...it will be pretty obvious wether there were collisions or not. The trigger is a plastic housing with a metal core that just "looks" at the trigger strip on the flywheel. If it got smacked...it may have easy to see evidence.

Did you ohm the CDI yet? Just to save you from all the other work first...

Another thought...take a good look at the CAST portion of the stator plate (will requre popping off the flywheel so check the trigger stuff first) could have easily gotten broken or cracked too.

If it turns out to be a pulverized trigger...Ricks Motorsports Electric is right in my town. Im sure if it isnt available...he has one. If Livewire doesnt have a replacement number of course lol.
« Last Edit: September 07, 2012, 04:39:50 PM by Factory 45 »

Gene

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Re: No spark sometimes
« Reply #10 on: September 08, 2012, 08:51:46 PM »
I tore apart the electrical side of the odyssey today.  I couldn't see anything wrong so I pulled the flywheel and I have the stator sitting on my bench,  Not having another one to compare it to I would guess the pulse generator has been beat a bit.  I would expect the center electrode to be flat or maybe somewhat curved to match the flywheel arc, but it appears to be ground down about halfway across its face making it higher in the middle. The plate appears to be ok as does the stator.  The multimeter says the neither the stator or pulse generator is grounded to the plate.  Is there any way to test the pulse generator?   I have included a couple images but my camera isn't great for closeups.    

Factory 45

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Re: No spark sometimes
« Reply #11 on: September 09, 2012, 06:05:40 AM »
There are 2 ways I have found...one involves an analog ociliiscope. (not an easy tool to setup/read without extensive experience AND a good graticular reference of a good trigger signature) The second is somewhat of a thing I have found...but I have a Fluke 87 that is very sensitive and excellent at catching tiny drops and spikes. (to me its like a scope without the setup crap)

Your meter when turned to ohm/res test...sends a small measurable voltage signal out of the red lead. Use the regular way to test the trigger with the meter (trigger on the plate...flywheel on the engine) With the meter on the trigger...rotate the engine a few times slowly... and watch your meter when the trigger strip comes close to the trigger (value of res will change...) I HAVE FOUND (and its NOT a 100% test...and the manual WILL NEVER indicate this test) that if during a rotation of the engine...your meter indicates ANY loss of the circuit...the trigger is bad. (sometimes if you have an AUTO Ranging DVOM...it can be tricky because the meter will switch ranges during this test)

I have seen volt signatures on a scope...and a hall switch (like a CKP CMP on a car) leaves a distinct drop/spike...which is a representation of what the system sees. My experiences are if the trigger (or CKP CMP) CANNOT support the spike/drop it will show a loss of circuit somewhere in engine rotation. (on your multimeter) You will NEVER catch this without a good meter or a scope...an intermittent open coil of any type is tricky to catch.

Hall switches and trigger coils are nothing but little magnets (which is why they get fuzzy with tiny steel pieces over time) Again...if the system doesnt see a CORRECT reaction to the trigger getting near the strip...NO spark/weak spark.

Pics really didnt help...but if the metal head (sticking out of the plastic trigger case) isnt flat topped and smooth...it got hit/rubbed. Take a look just around the metal for tiny cracks in the plastic. 

« Last Edit: September 09, 2012, 06:30:31 AM by Factory 45 »

Gene

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Re: No spark sometimes
« Reply #12 on: September 09, 2012, 05:37:20 PM »
Thanks for all your help, especially Factory 45 and Livewire.  The trigger has a small crack and with the magnet/face damaged I will replace it if I can find one since it is off the engine already and I know I have a problem anyway.
My multimeter is a Fluke 77/AN that I inherited from my father in law. I will have to try the tests you suggested just for practice. 
I found a complete unit on ebay and from the picture it looks like the center face is proud of the plastic which mine isn't.  If I can find a replacement pulse generator I suspect that may be cheaper.  The wires coming out of the pulse generator are different than the ones in the wire loom so there is a splice already so it should be easy enough to graft in a new one.
My initial search didn't turn up a source for a pulse generator but I will check around more this week and see what I can come up with.   

Factory 45

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Re: No spark sometimes
« Reply #13 on: September 10, 2012, 05:10:49 AM »
I would try getting a number for the trigger in the aftermarket. Sucks to say but the quality of these types of components has fallen off over time. Good news is that looks like a very typical part used on alot of honda "stators".

You are very welcome for the suggestions...however these type of problems can be frusterating. My suggestion (on any diagnostic type job) is to completely test all components and draw your conclusions based on the results of your tests...and the data you record. Try to gain the best understanding of the system before making your decision. Be patient...and keep it simple when all else fails.

Any Fluke is good in my book...the cheaper meters are just for testing volts and wire harnesses. Anything technical...needs a GOOD meter.

My bet on this issue is its going to be in the stator (trigger or exciter) possibly stemming from the twisted crank.

Some of the other CDI units that use 12v DC for power (electric start and EFI models mostly) I have seen get hurt and burn out due to harness shorts and such...but the simple AC only systems come down to signal input and output. There really usually isnt enough available power to cause melt downs or high current shorts that cause major solid state component damage.

Gene

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Re: No spark sometimes
« Reply #14 on: September 16, 2012, 10:48:26 PM »
I have spark!!  After a having no luck this week finding a replacement pulse generator I thought nothing ventured, nothing gained, so I filed the magnet flat on mine, enlarged the holes on the mounting plate, in the absence of a spec I set the gap from the magnet on the flywheel to .010 inch.  I got a spark even with the plug in the cylinder head and another in the wire laying on the head.  I have the day off work tomorrow so I will put everything back together and hopefully she will run.