FC420V won't start

[Harold41]

I have a Kawasaki FC420V in a John Deere LX182 that won't start. After 4 or 5 cranking attempts it will ignite the fuel in the muffler with a loud bang. I have replaced the coil, ignition module, spark plug, flywheel/crank key. I also checked the valve lash and compression. Compression was 80+ PSI. Spark tester shows spark. Using ether makes little difference. This happened a few times in the past and I was able to restart by boosting with a car battery, but this time it doesn't help. Sounds like it some kind of timing issue. Does anyone have an idea what to try next.

Harold Wilson

 

[Darryl G]

Hi. This is a bit of a hunch, but I had a similar problem with one of my Kawasaki engines. How fast is it turning over? It could just be a bad battery or worn starter drawing too hard and not spinning fast enough. If the battery is far enough gone even jumping it won't send enough "juice" to the starter to spin the engine fast enough to fire.

 

[Harold41]

It's always seemed to turn over slowly to me but hasn't changed recently. Guess I'll pull the starter and see. There is a test in the manual for the starter but you need a way to measure the free spinning starter RPM's.

 

[Darryl G]

I'd try to jump it directly from a good battery to the terminals first, eliminating your mower battery, and see if that works.

 

[Harold41]

I tried substituting my tractor battery with no success. Then I remembered this is a metric engine. I pulled the flywheel and mic'd the key. The original key mic's 0.197". The replacement from the hardware store mic's at 0.187". Checking the other measurements the key looks to be a 5 X 6.5 x 15.7 mm key. Guess I'll order a metric key. I don't find my exact model listed its a FC420V-AS10. I find listings for AS09 & AS12 and they are both the same key.

I attached a photo of the old key. Is 0.010" difference enough to get the timing off enough to not start?

 

[Luffydog]

Do a leakdown test of each cyclinder. Compression seems a little low. Might not be firing under compression very good

 

[Harold41]

I picked up an OEM flywheel key at the John Deere dealer today and installed it. Still doesn't start. Today with ether I could get a couple backfires from the carb which it hasn't done before. Took the fuel hose loose and the pump puts out plenty of volume. Also checked the carb bowl, it has fuel in it. Looked at the spark plug and it wasn't wet like I would expect.

I did try my homemade leak down tester (air tee'd into a compression tester) earlier. At 40 PSI I could only detect leakage by the rings. I think I need to re-do the compression test with adding oil thru the spark plug hole.

May have to put on hold a few days, It's supposed to be dry here & I need to do some gardening and mowing. I don't use this one to mow anymore, just to pull a trailer and a sprayer.

 

[bertsmobile1]

Never liked using either I preffer to use caarb cleaner, much easier on the engine & does not diesel in a mower engine.
So give a shot of fluid down the plug hole & crank the engine.
Engine fires = valves are sealing & timing is good.
do the same down the carb throat.
Engine does not fire, valve timing is bad
engine does fire , = fuel problem.

You never told us why it stopped running in the first place and this is important cause you may have skipped or broken a tooth on the cam shaft.

 

[Harold41]

It didn't stop on it's own. I shut it off. Then when I went to restart it a few min later it wouldn't restart. This actually happened a couple times before when I had a weak battery in it, then when I towed it back to the shop it restarted with a boost. This last time it has a new battery and also will not restart with a boost.

I'll try shooting carb cleaner into the spark plug hole tomorrow.

 

[Harold41]

I shot some carb cleaner into the spark plug hole, replaced the spark plug & cranked. What I got was a loud bang & blaze from the muffler. Did this a second time with the same results. I then put a shot of carb cleaner into the carb throat. I got 2 or 3 mild backfires thru the carb. Tried it a second time and got a laud bang & fire from the muffler & then 2 or 3 backfires thru the carb.