Kohler CV18S on an old Ford LS55

RandyAdcox

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Hi all,
Recently inherited an old Ford LS55, which has a Kohler CV18S engine. Original owner tells it me "was running a couple of years ago, but started running ragged, and so it was parked and replaced with a new mower". Engine seems to have good compression, but I've determined that I have no spark on the "right" cylinder (if you're sitting on the tractor). Spark is good on the other cylinder, but engine refuses to even try to start. Installed a new battery, so have plenty of "power", but engine does nothing but spin...never even attempts to "fire". Found a service manual online, which references an ECU module, and associated EFI system.
I originally thought perhaps I had a bad coil on the right cylinder, but now I'm wondering if maybe this is an ECU/EFI problem. Don't know if it matters, but here is the Spec#: 61515, and Sr#: 2417510117. Anyone got any thoughts/ideas/suggestions for this admitted "rookie small engine mechanic"? Thanks!

Update!! Confirmed the "right" coil is indeed bad (swapped coils and the problem went to the other cylinder). Still curious as to why the dang thing doesn't even attempt to crank on the one, "good" cylinder, but anyway, will order a new coil and see what happens after it's installed.
 
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ILENGINE

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No ECU or EFI on that engine, just straight carb. Could possibly be that both modules are bad. May fire if plug grounded to head, but not fire under compression. Remove the blower housing and disconnect the kill wire from the modules and recheck for spark. The correct tester has a gap of close to a quarter inch. So the closest you can get would be a plug with the side electrode removed.
 

RandyAdcox

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No ECU or EFI on that engine, just straight carb. Could possibly be that both modules are bad. May fire if plug grounded to head, but not fire under compression. Remove the blower housing and disconnect the kill wire from the modules and recheck for spark. The correct tester has a gap of close to a quarter inch. So the closest you can get would be a plug with the side electrode removed.


Thanks for your quick reply to my original post. Please forgive my limited understanding of your response, but I'm not sure I follow the last sentence in your response. The way I "tested" the modules, was to unplug the wire from the spark plug, insert a screwdriver into the hole, and then hold the screwdriver close to the tip of the spark plug while turning over the engine. I can see a spark jump from the screw driver, to the tip of the plug on the "good" cylinder, but I don't get any spark at all on the other cylinder. As mentioned earlier, I swapped the modules, and the "problem" went to the other cylinder. Am I understanding you to say that the module I'm thinking is "good"", could actually be "bad" (even though I'm getting a spark from the screw driver to the tip of the spark plug)? I also took a piece of sandpaper and "cleaned up" the surfaces of both modules, as well as the magnet on the flywheel (all 3 surfaces had a thin film of rust on them). If you think I should go ahead and replace both modules, I'm "ok" with doing that, just wanted to make sure before I order both of them, that both are indeed "bad".
While I've got your attention, I'm concerned that this engine may have been sitting for a few years, with gas in the lines and carburetor (the gas tank was dry when I obtained the mower, and the original said it hadn't run in a few years). I really don't relish the idea of having to rebuild the carburetor (or pay someone else to do it), but do you think I need to do anything in particular with the carburetor? I've got some carburetor cleaner, and I've already sprayed it all over the outside of the carburetor housing and into the throat, but I haven't removed the carburetor or done any other "cleaning".
Thanks again for your help/input! I really appreciate it!
- Randy Adcox
 

ILENGINE

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If you moved the module to the other cylinder, and the problem moved to that cylinder then I would say that module is bad. You can replace that one and will probably be good. I have had some cases on Kohler engines were the second module would fail shortly after replacing one, but not all the time. the engine should start and run on one cylinder, Have you tried putting some gas into the intake and seeing if it would start and die. If it dies then you will probably need to do internal carb cleaning.
 

RandyAdcox

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If you moved the module to the other cylinder, and the problem moved to that cylinder then I would say that module is bad. You can replace that one and will probably be good. I have had some cases on Kohler engines were the second module would fail shortly after replacing one, but not all the time. the engine should start and run on one cylinder, Have you tried putting some gas into the intake and seeing if it would start and die. If it dies then you will probably need to do internal carb cleaning.

Thanks again my friend. I actually DID spray some of the carburetor cleaner into the intake of the carburetor, and tried turning the engine over, but it didn't "fire". Granted it wasn't gas, but since it was flammable, I kinda thought it might at least sputter or something...perhaps not. Will try some gas tomorrow and see what happens. Back to the modules for a moment....I actually found a "pair" (of new ones) on Amazon for $92...seemed like a decent price considering most places wanted $60 (or more!) for one. That sound like a good price to you? If so, I think I'll just go ahead and order both, and replace 'em both. It's a bit of a chore to get to the dang things...kinda makes sense to me to go ahead and replace both of 'em anyway.
Again, I really appreciate your help. Will keep you posted as to my results.
- Randy
 

RandyAdcox

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Thanks again my friend. I actually DID spray some of the carburetor cleaner into the intake of the carburetor, and tried turning the engine over, but it didn't "fire". Granted it wasn't gas, but since it was flammable, I kinda thought it might at least sputter or something...perhaps not. Will try some gas tomorrow and see what happens. Back to the modules for a moment....I actually found a "pair" (of new ones) on Amazon for $92...seemed like a decent price considering most places wanted $60 (or more!) for one. That sound like a good price to you? If so, I think I'll just go ahead and order both, and replace 'em both. It's a bit of a chore to get to the dang things...kinda makes sense to me to go ahead and replace both of 'em anyway.
Again, I really appreciate your help. Will keep you posted as to my results.
- Randy

Ok...Managed to get some gas into the carburetor intake today, and she fired right up! For a 23 year old engine, the ol' girl ran pretty good - to be running on one cylinder! Gonna order a couple of ignition modules tomorrow, and hope to see this ol' girl purring like a kitten here in a few days! Thanks again for your input and help!
 
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