Mower won't start...sheared flywheel key?

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  #1  
Old 08-03-17, 04:30 PM
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Mower won't start...sheared flywheel key?

https://www.dropbox.com/s/por9dsm5we...44449.mp4?dl=0

Hi,

I am having trouble starting the mower in the attached video. It ran fine last fall, although it's always been difficult on the pull start - there's a hitch, and sometimes it can snap back out of my hands. I ran it dry and put ethanol free fuel in it before winter, but couldn't get it started this spring (almost turned over once, but that was it). So I cleaned the carb (which didn't look bad), reassembled.

Still won't start - maybe the flywheel key is sheared? I don't have a flywheel puller and don't want to screw it up anymore than it already is. It's a Kawasaki FC420V OHV motor, pretty common (I think) so I'm hoping someone else may have dealt with a similar issue.

Any help is much appreciated.

Thanks,
 
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  #2  
Old 08-03-17, 04:43 PM
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No, nothing to do with the key.

I'm assuming you don't have the mower blade engaged by accident... and it's in neutral.

That engine has a compression release and if it is hard/jerky to pull, that's the problem. Either the valve lash needs to be readjusted or you just need to pull hard enough to get it to open up.

Try taking the spark plug out and pull... it should pull as easy as pie. Let us know what you find. You might need to take the head off and ensure the valves are both working... and assuming they are, check the valve clearance with a feeler gauge to see if they are within specs.
 
  #3  
Old 08-03-17, 04:52 PM
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Thank you Xsleeper - it's much easier to pull when I remove the spark plug. No, the mower wasn't in gear or the blade engaged. The engine does say "automatic compression release" on the top. I'll look into taking the head off and checking the valve lash. Thanks!
 
  #4  
Old 08-03-17, 04:59 PM
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This video might help you out. https://youtu.be/x_TrpVFWTQE

Keep an eye out for the pros... they will be along soon.
 
  #5  
Old 08-03-17, 06:29 PM
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Whoa! Don't go pulling the head off to check the valves

Just pull the valve covers as in the video and see if any thing is off track.
 
  #6  
Old 08-03-17, 11:12 PM
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Thanks to both for the help. In order to manually rotate the crankshaft, I think I need to turn the bowl (for lack of a better word) here clockwise (see attached pic), based on the direction of the pull start mechanism. How do I turn this? It didn't move when I tried gently by hand, and I didn't want to force anything.

Thanks!
https://www.dropbox.com/s/q3jhujb3ju...81%29.jpg?dl=0
 
  #7  
Old 08-04-17, 05:04 AM
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First, make sure the spark plug is removed. You can turn the "bowl" you mentioned but I usually turn the blade as it provides more mechanical advantage and makes it much easier to turn.
 
  #8  
Old 08-04-17, 03:04 PM
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I adjusted the valve to the specs indicated by the manufacturer (it had too much clearance at TDC previously). Still won't start though. Attached another video. Still gets hung up partway through the pull start sometimes, but overall less resistance and smoother, I think I'm generating enough compression on the pull, but maybe I need to buy a compression tester? Just don't know.

Thanks,

https://www.dropbox.com/s/fk93qbb6xp...04061.mp4?dl=0
 
  #9  
Old 08-04-17, 03:25 PM
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It's the exhaust valve gap that is finicky. That's what opens the compression release. At top dead center, the exhaust valve needs to be cracked open to relieve the pressure at startup. Check the gap again and be sure you have the piston turned all the way to top dead center and that you are setting the gap correctly. I'm guessing you still have the exhaust valve set too loose.
 
  #10  
Old 08-04-17, 03:26 PM
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That doesn't sound abnormal for that engine...
Have you checked for spark?
 
  #11  
Old 08-04-17, 03:29 PM
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If the compression release is on the exhaust then you want to go 1/4" past TDC to correctly set the clearance, otherwise you will end up with too large of clearance.
 
  #12  
Old 08-04-17, 04:07 PM
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I think the 1/4" past TDC applies to some B&S and other engines maybe - I attached the service manual for this engine, which specifies TDC. I realized after the video I forgot to check the clearance for the intake valve, so I adjusted this and also tweaked the exhaust valve - result is that the pull start is even smoother, but still nothing. Next I'll have to check for spark I think.

https://www.dropbox.com/s/77gh8hglut...specs.pdf?dl=0
 
  #13  
Old 08-04-17, 06:13 PM
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Did you follow that last bit of instruction about testing to see if the ACR is faulty?

Yes, testing for spark should be a no brainer... you mentioned the flywheel key earlier... I dont know if you suspect it but the flywheel key only shears when you hit something with the mower blade and the engine stops suddenly. (Like a tree stump)

If you have spark, next thing is fuel.
 
  #14  
Old 08-05-17, 10:34 AM
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I checked spark plug gap (it was way off), and adjusted this to proper. Still didn't work. I cleaned the old spark plug (which worked fine) and tried this, still doesn't work. I couldn't find my torque wrench so maybe the plug isn't tight enough, but I doubt that's the problem.

The ACR does appear to function - per the PDF in the prior post, it notes the exhaust vale should open at least 0.6 mm briefly just after the intake valve closes. I didn't measure, but it does open a little after the intake valve closes. Again, the pull start is much more manageable now.

There wasn't any fuel delivery issue before, can't be sure though.
 
  #15  
Old 08-05-17, 10:42 AM
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Hold the plug in you hand while you pull the starter... if you have spark you will feel it. If you dont thats the problem.
 
  #16  
Old 08-05-17, 11:53 AM
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It looks like no spark - I tried the test (see video) with the plug grounded against metal, as well as when holding it w/pliers. I tried both plugs as well. Maybe the spark plug wire is bad?

https://www.dropbox.com/s/2yjveet7pp...98330.mp4?dl=0
 
  #17  
Old 08-05-17, 04:41 PM
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Without knowing more about your engine its hard to say. We dont know if you have electronic ignition or points and condenser. And we cant rule out the flywheel key if the last person to use it hit something. Maybe check to see if it has an igniter... if it does you can test it to see if its working.

https://www.youtube.com/watch?v=YbDEswIULWE
 
  #18  
Old 08-05-17, 06:38 PM
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Disconnect the wire that plugs onto the coil and see if you get spark then. If not, make sure the coil is properly gapped and if so, you have a bad coil.
 
  #19  
Old 08-06-17, 08:20 PM
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Thanks to both for the help. It is electronic ignition, but no I don't see an ignitor on the side of the motor like in the video posted by XSleeper. There is also the muffler in the way on that side of the engine.

To access the ignition coil, it looks like I will have to start taking some things apart. I have attached a PDF of the ignition system coil and control unit check from the FC420V service manual.

https://www.dropbox.com/s/nbn7llftl9...check.pdf?dl=0
 
  #20  
Old 08-07-17, 06:20 PM
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Looks like a couple of 10 mm bolts to remove the engine shroud, to access the ignition coil. However, I think I need to first remove the 3 bolts on the bowl (see attached) that connects to the flywheel. I tried with a hex head drill bit, however it just spins the whole flywheel. Not sure what I'm missing, but any help is much appreciated.

Thanks,

https://www.dropbox.com/s/bydkwn5hv4...10921.jpg?dl=0
 
  #21  
Old 08-11-17, 09:31 AM
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I was able to access the ignition coil. Resistance from the primary terminal to core tested fine (0.5 - 0.7 ohm), but the plug lead to core test measured 0.4 M ohm, or 400 K ohm. This should only have been 10.9 - 16.3 K ohm, so there is too much resistance.

I can get a new ignition coil today for $86, so I think I'll try this.
 
  #22  
Old 08-11-17, 12:35 PM
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I went ahead and got the new ignition coil, gapped it and put it on and put everything back together...still no spark.

So I took it apart again and removed the kill wire and put it back together, finally have spark!

Is it just a matter of replacing the faulty ground wire at this point, or could there be other things I have to test?

Thanks,
 

Last edited by aerodan1; 08-11-17 at 12:51 PM.
  #23  
Old 08-11-17, 01:09 PM
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They can be finicky sometimes. It must have been going to ground when it shouldn't have been. I doubt the wire itself is bad... if the kill switch is part of the throttle cable adjustment perhaps the linkage just needs to be adjusted.

sounds like you are making progress.
 
  #24  
Old 08-11-17, 01:51 PM
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Thanks for the help - I don't think the kill switch is part of the throttle cable adjustment, but I'll keep this in mind. I'll try to get a video up to show the path the wire takes from the coil back to the ignition key.

Thanks,
 
  #25  
Old 08-11-17, 03:10 PM
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I took a video tracing the ignition wiring, but then I then up cleaning the contact at the ignition switch. I saw it was getting spark with or without the kill wire attached (spinning the flywheel by hand it was weak spark either way).

So I left the kill wire attached and put the shroud back together. Attached is a different video I took - it still won't start. You can observe a spark (although weak). The second half of the video no spark since I turned the key off.

https://www.dropbox.com/s/x9mo643u91...13232.mp4?dl=0

Update: I tried again just now with the old spark plug. Stronger looking spark, still no start though.
 

Last edited by aerodan1; 08-11-17 at 03:48 PM.
  #26  
Old 08-11-17, 03:53 PM
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You need to replace the igniter, although you have spark it is probably at the wrong time, I had a fc150 that wouldn't start and had lots of spark, it would spark but very erratic. Rotary has the igniter for about $20 the Kaw part is much more expensive. Have a good one. Geo
 
  #27  
Old 08-11-17, 03:55 PM
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Thanks but this is a later model FC420V - there is no separate igniter.
 
  #28  
Old 08-12-17, 10:21 PM
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Tried a quick squirt of starter fluid just to see whether I had a fuel issue as well. It didn't start. I do have plenty of compression I think, fuel shouldn't be an issue, and I have spark, but maybe not strong enough. is there an easy way to test spark strength?

Thanks,
 
  #29  
Old 08-19-17, 12:22 PM
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I tried starter fluid again on a few occasions - this gets it to turn over and run for a second, and then it stops. Pulling on the starter cord, I remove the spark plug and it's dry. I know fuel is getting to the carb (and I put in fresh fuel), and I put a new fuel filter on. The float and carb seem to be working properly - nothing seems off to my eye when I took it off today. I didn't mess around with the mixture screws previously when I cleaned the carb, so I'm not sure what the issue is at this point, but definitely seems like a fuel issue at this point.
 
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