Money is on a sheared key.
Posted via Mobile Device

 

An inline tester is pretty foolproof. If it shows a spark, you got spark. Are you unfamiliar with popping off the flywheel?
Posted via Mobile Device

 

Since I'm still learning about diagnostics, I (and others I'm sure) will be interested to hear about your successful solution.
cheers.

 

Sheared flywheel key. Don't pry or beat on the flywheel, unless you like buying extra parts for nothing.

An experienced mechanic will put a pry bar under the flywheel with slight tension on it while he raps the partially rethreaded on retaining nut with a dead blow hammer. Pops off every time no damage. But, like I said an experienced mechanic.
Posted via Mobile Device

 

I too really wish you had cleaned the head by hand while it was apart. Seafoam probably won't remove much carbon. It's a flammable solvent so it's already burnt up going past the exhaust valve. You could have soaked it and gotten it 90% clean. I thought you had tried the plug to ground thing first?
Posted via Mobile Device

 

Just reading of the post how rust can effect some engine parts .

Should rust be removed from flywheels & ignition coils ?

What is your way of clean corroded & rusted earth wire mounts ?

 

I'm not a mechanic so the information here will be expanded upon by others more knowledgeable than I, but the main rule of thumb is FAST. Fuel Air Spark Timing and work them in that order. Spraying quick start should get the engine to sputter regardless of the carb being functional or not. I assume you have the air cleaner removed for all of this.

Drying out a flooded single cylinder is in the order of 10-15 minutes, not an entire day. You used an-inline spark detector but you didn't mention testing the plug itself. Substitute a known good plug, even if its the wrong type-you can replace for the correct one later. If you can't get it to sputter, then the timing may be wrong. Does it look like the engine has had recent work? Folks will worry at an engine, change settings, give up and put it out at the curb. Don't assume that it was reassembled correctly.

 

Thanks for the reply. The spark tester connects the spark plug to the spark plug boot, so it was testing both the coil and the plug. Although the spark tester confirmed the presence of spark, I am a little skeptical about the plug. It looks brand new, but it's an e3-10 plug. I looked it up, and it does cross reference with the Champion RJ19LM that is supposed to be in the motor. I have a new Champion plug on order, just in case it is the plug.
It doesn't look like anyone did any recent work to the mower other than to put in a new plug and a brand new air filter. They probably gave up after that.
I tried it again after leaving it in the sun for a couple hours, and still nothing. I can get it to sputter once if I remove the carb and spray starting fluid directly into the cylinder. But it will only do it some of the time.
Which makes me think that you may be on to something with the timing. I work on a lot of weedwackers, so I am very familiar with their timing system. I'm not so versed on lawnmower timing, though. Am I right that it isn't that different than a weedwacker in that there is a magnet on the flywheel that triggers the coil on each rotation? If so, is there any way for the timing to be off? I thought this system was basically fool proof, unless the flywheel key gets sheared (or partially sheared). Is there something I'm missing? Thanks!

 

Thanks for the reply. The spark tester connects the spark plug to the spark plug boot, so it was testing both the coil and the plug. Although the spark tester confirmed the presence of spark, I am a little skeptical about the plug. It looks brand new, but it's an e3-10 plug. I looked it up, and it does cross reference with the Champion RJ19LM that is supposed to be in the motor. I have a new Champion plug on order, just in case it is the plug.
It doesn't look like anyone did any recent work to the mower other than to put in a new plug and a brand new air filter. They probably gave up after that.
I tried it again after leaving it in the sun for a couple hours, and still nothing. I can get it to sputter once if I remove the carb and spray starting fluid directly into the cylinder. But it will only do it some of the time.
Which makes me think that you may be on to something with the timing. I work on a lot of weedwackers, so I am very familiar with their timing system. I'm not so versed on lawnmower timing, though. Am I right that it isn't that different than a weedwacker in that there is a magnet on the flywheel that triggers the coil on each rotation? If so, is there any way for the timing to be off? I thought this system was basically fool proof, unless the flywheel key gets sheared (or partially sheared). Is there something I'm missing? Thanks!

your right probably sheared the flywheel key

 

Did you actually SEE the spark at the plug gap or was it inside the engine while you were using the tester? If not, then remove the plug from the head and test it in contact with the head, preferably indoors so it will be easy to see the spark. If you were using a gap tester outside the engine that still doesn't prove the plug has spark. All you know is that voltage is getting to the plug tip. There may be a carbon track on the plug that diverts the voltage to ground and you end up with a weak spark or no spark.

About the coil, all I can offer is that the coil gap needs to be exactly right. You need to look up the correct gap for that engine. If you don't have a feeler guage, buy one as they have a multitude of uses and are not expensive. If you happen to be hours away from a store, you can use a business card to set the gap.

I'm hoping someone else chimes in as with my limited skills I'm running out of ideas(LOL)

 

Patriot and I Mow Alone, thanks for the input. Working on weedwackers, I don't see many sheared keys because the string is sacrificial. I guess lawnmowers have sheared keys more often because they don't give when they hit rocks. Reminds me of the argument in favor of aluminum or composite props instead of stainless. Boaters with stainless props destroy their gearcase when they hit a rock, unlike experienced boaters who stick with the "cheap" props for good reason.
Unfortunately, I don't have a 15/16" socket or a strap wrench, so I cannot check the shear key yet. I am going to see if I can pick one up tomorrow and will post a follow up. Thanks again!

 

Edinottowa,
Thanks for the reply. I did not actually see the spark because the plug was in the cylinder. This method has never failed me on a weedwacker, but I see your point about the carbon track. I will retest it against the block.
I do usually use a business card for the coil gap. I will look into the correct gap for this motor and check it against my spark plug feeler gauge (not the round feeler gauge. I have the one that is a book of individual sheets of metal of varying thicknesses).
Thanks!

 

You don't need a strap wrench to loosen the flywheel, pin the blade with a block of wood......

The light type spark testers can lie, if in question always check spark with plug out and shorted to ground.

While you have the top cover off check the plastic intake manifold, make sure it's not broken and tight on the engine block.

Also, this engine has a plastic cam gear assembly, I've seen wiped lobes and stripped teeth. Either will cause the valves not to open, and yes you can get a good compression reading with the valves staying closed.

I got 180 lbs on both cylinders on a twin Kawasaki with half the steel cam teeth wiped off.......

 

Sheared flywheel key. Don't pry or beat on the flywheel, unless you like buying extra parts for nothing.

 

Restororob, thanks for the input. I'm going to try the "plug to ground" test tomorrow. Just have to put the mower all back together before I can do it. The plastic intake manifold is intact, and tight to the block. I removed the cylinder head to make sure the valves were working, and both of them open and close normally. They are full of carbon, but functioning. When I get this mower running, I'm going to run some Seafoam through it.
Thanks for the heads up about the plastic cam gear assembly, I'll try to find a video on it so I can understand it better. I will try the block of wood instead of the strap wrench, but I can't get that far yet because I need a 15/16" socket. My set only goes up to 7/8". I'm new to lawnmower repair, so I will have to add some tools to my small engine repair toolbox, which is currently geared for small two strokes. Thanks again!

 

Patriot, thanks for the tip... I've seen that on Youtube. I just can't get to that point until I get the right socket size.

 

You could also look for rust on the flywheel too. I have had a rusty flywheel cause intermittent spark on a cheap push mower. Took a while to figure that one out and man did I feel stupid when I realized I had looked at the problem at least 5 times! Clean the spark plug with starting fluid and burn it off. This will take care of any moisture issues just be sure to clean the plug with some sand paper after.
Posted via Mobile Device

 

First, thank you all for your valuable input. Every reply helped me understand the problem by looking at it from different angles. This forum is a very powerful brainstorming tool!
Here's how it went down... I tried the spark plug in my buddy's mower and his mower would not start. I bought a new plug (Champion RJ19LM), put it in, and what do you know... fired on the first pull! I mowed the lawn with it, stopping and starting it several times... works perfectly.
Edinottowa and Restrorob, you guys were right about having to SEE the spark. I've fixed about 100 weedwackers, and have always relied on my inline spark tester, and it has never failed me. I have to agree with Patriot that for the most part, you can rely on them. But from now on, I am only going to rely on it to tell me if the coil is producing spark. The next time I can't get something started, I will try a new plug before going any further.
Thanks everyone!

 

Restororob, thanks for the input. I'm going to try the "plug to ground" test tomorrow. Just have to put the mower all back together before I can do it. The plastic intake manifold is intact, and tight to the block. I removed the cylinder head to make sure the valves were working, and both of them open and close normally. They are full of carbon, but functioning. When I get this mower running, I'm going to run some Seafoam through it.
Thanks for the heads up about the plastic cam gear assembly, I'll try to find a video on it so I can understand it better. I will try the block of wood instead of the strap wrench, but I can't get that far yet because I need a 15/16" socket. My set only goes up to 7/8". I'm new to lawnmower repair, so I will have to add some tools to my small engine repair toolbox, which is currently geared for small two strokes. Thanks again!

FYI you could have/ nay should have mechanically scraped the carbon from the piston, head and valves. A lot of times I actually use a small scraper, and hand wire brush on the valves and seat area, while they are fully open, then follow with a doobie pad and some compressd air. Works every time.
Remember: It ain't a race motor, it's a freakin lawnmower motor. pretty basic, crude and simple, right?

 

Few things I have learned...

A coil can give a spark both via the plug-to-ground or the tester light method...
And yet the coil still needs replacing, mostly because it's too weak a spark.
This has done happened to me twice in the past 14 years, the second time not a week ago.
It about frustrate me to tears.

And a carburetor can appear to be working as it's supposed to...
And still need replacing.

Same goes for a spark plug, sometimes just putting a new one in fixes it.

I mean at some point if all else fails you just have to start replacing parts...
Why some of us become brand loyal, is after so many years we usually have some working spares laying around we can plug in (as in literally replace a coil with a working spare just to eliminate that once and for all), and so on...

Gets to where you may have to replace first the coil, then the carburetor...

Last but not least, IF (or WHEN) you replace a carburetor on an older machine ALWAYS replace the gaskets.
It's just one of those things, you want to replace things ONCE and done.
So that there's a true process of elimination...
Even then I've had to pull the same part off (and re-install) more than once.
We try to avoid ^ this ^ scenario as much as possible.

Best of luck, hope you get it worked out soon.

 

BigFish and Patriot,
I only have to remove 8 bolts to get to the valves and piston, so I'll scrape it and clean it tomorrow. Then Seafoam it. I'm a boater, you can't deny me my Seafoam!
I wanted to try the plug to ground thing yesterday, but the mower was in a million pieces. Once the E3 plug that came with the mower failed to work in my friend's mower, I knew I had found the culprit. So I never did do the "plug to ground" test, although there's no doubt it would show spark.
As for spark strength, I have another spark tester that shows the spark jumping the gap. For weedwackers, I set the gap to "SA". Does anyone know if this would be the same gap setting for lawnmowers?

 

Herler,
Thanks for the insight into how you work through a diagnosis by ruling everything out very methodically. I, too, have had carburetors that I think are very clean, and that pass the pressure test, but are not good carbs. That can drive you crazy. For weedwackers, I have "known good carbs", and "known good coils", and such. I'm new to lawnmower repair, but I'm sure in time I'll be like you and have some of the standard parts that I keep on hand for diagnosing problems.

 

Herler,
Thanks for the insight into how you work through a diagnosis by ruling everything out very methodically. I, too, have had carburetors that I think are very clean, and that pass the pressure test, but are not good carbs. That can drive you crazy. For weedwackers, I have "known good carbs", and "known good coils", and such. I'm new to lawnmower repair, but I'm sure in time I'll be like you and have some of the standard parts that I keep on hand for diagnosing problems.

I'm sorry man.