John Deere 425 Turned over but will not start, backfires

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Old 02-15-21, 06:02 PM
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John Deere 425 Turned over but will not start, backfires

I have a John Deere 425 AWS with a Kawasaki FD620D. Which has been a solid workhorse until now.
My Issue was a coolant leak on top of the engine. Front engine cover gasket failed. So, I pulled the Engine. Pulled water pump, water pump housing, and main engine cover from engine being careful not to disturb the Cam Gear or any other Internal components. Good News. No Oil In Coolant and no Coolant In engine.
Put engine cover back on. Installed new gaskets, water pump, main seal, valve cover gaskets, plugs, coil packs, Fuel solenoid, Air Filter, fuel filter, fuel lines, clamps, oil/filter, coolant, new battery. Starter/solenoid Is 30 days old. Bad News: Engine turns over but does not start. I have spark on both sides. The engine will back fire. Flames come out Carb. Any help would be great?

 
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Old 02-15-21, 06:26 PM
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Disconnect one of the coils - all the wires to that one and see if it will start on the one that is still hooked up.
 
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Old 02-15-21, 07:57 PM
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Sounds like the timing is off. Did you remove the flywheel?
 
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Old 02-15-21, 08:15 PM
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Or maybe you got the wires swapped on the pickup coils. Is this a pre 1998 engine with the plastic cams? Could be a bad cam gear too.
 
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Old 02-16-21, 05:27 AM
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"So, I pulled the Engine. Pulled water pump, water pump housing, and main engine cover from engine being careful not to disturb the Cam Gear or any other Internal components." Not sure what this means as I have never worked on a Kawasaki engine. There are 2 things I would check. First remove the flywheel and insure alignment key doesn't have an offset or shear. Replace if either. Second, I would check the spark timing to cylinder 1 by observing spark magnets on flywheel relative to ignition module with flywheel rotating in the run direction. Good luck.
 
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Old 02-16-21, 05:56 PM
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And it was running fine right before it? I'd look at the flywheel key first, as others have said.
 
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Old 02-20-21, 09:54 AM
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Backfiring out the carburetor could be due to the intake valve sticking open when the cylinder fires. You typically won't have a sheared flywheel key unless the engine had a hard and sudden stop.
 
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Old 02-20-21, 08:23 PM
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Generally you don't have two intake valves stick open simultaneously either.
 
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Old 02-20-21, 08:53 PM
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#1, Why not? #2, I didn't see anywhere that it said both cylinders. Was a compression or leakdown test performed?
 
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Old 02-21-21, 08:40 AM
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If it was running fine and now it is acting strange I would say the igniter has gone bad. Have a good one. Geo
 
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Old 02-21-21, 11:52 AM
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In my experience, an igniter either works or it doesn't. I've never heard of one failing as to fire a cylinder out of time. It was indicated that there is spark. If compression and fuel are present the cylinder should fire. So, what is compression? A cylinder leakdown test would indicate whether a valve is stuck open.
 
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Old 02-22-21, 05:45 AM
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The flywheel key alignment and crank nut torque shows up here a lot. If the flywheel was removed that would account for the problem. Usually it's just things getting a little off and the nut gets tightened.

Also with two coils the cross firing through the kill wire has shown up with the kill wire diode being the problem.

We need some feed back from the OP.
 
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Old 02-22-21, 12:33 PM
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I agree, if the flywheel key doesn't prove to be the problem I would disconnect the kill wire from the coils and try again.

glwjr, if both intake valves weren't stuck open, it would still crank up on the other cylinder. Pretty unlikely that both of them just randomly stuck open. I have also seen igniters on kawasakis that allowed the system to spark, but at the wrong time. I've seen that probably more often than complete failure, but mostly on the older models.
 
 

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