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So it all started when I decided that I should change the oil since I had not done that in about four years. I changed the oil and replaced the battery. Used the mower twice after that and both times it started fine, ran fine for about 10-15 minutes, cut off, refused to restart, rested for 20 minutes, started again fine and ran until I was done mowing (maybe an hour).

Now it will not start. I have the spark plug and cleaned the carb (outside was dirty, inside was not). Fuel flows perfectly fine to the carb. Fuel filter isn't blocked. The engine spins but doesn't start or really come close to starting. I thought maybe I overfilled it with oil... drained the oil... added new oil (30). That didn't help. I have spent roughly 10 hours working on it over a few days. I'm out of ideas and can't start the mower. Any help?

Briggs & Straton 19.5 HP engine.
Model: 31P677
Type: 0912 G5
Code: 121019ZD

Bought the mower new in ... corrected to 2013.

Pull the valve covers and check the valve clearances.

Rivets said:

Pull the valve covers and check the valve clearances.

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This is probably very good advice, but it is also above my skill level. I wouldn't know what I was looking at.

Pretty good video. This could very well be the problem, but that is over my level.

It is definately not above your skill levels
IT is just you have never done it before so it is confusing thus scary
Search You Tube for "Checking Briggs Valve Lash " or "checking valve lash on an Intek engine"
You should get 10,000 hits plus a lot of arguements over which method to use.
For the novice mechanic the factory 1/4 past TDC is the least confusing
Buy a new rocker cover gasket because yours will probably break when you remove the cover

Then apparently the engine has been replace or you use a time machine to get the mower. The engine was built October 19th, 2012. So it is more likely you brought the mower in 2013.

bertsmobile1 said:

It is definately not above your skill levels
IT is just you have never done it before so it is confusing thus scary
Search You Tube for "Checking Briggs Valve Lash " or "checking valve lash on an Intek engine"
You should get 10,000 hits plus a lot of arguements over which method to use.
For the novice mechanic the factory 1/4 past TDC is the least confusing
Buy a new rocker cover gasket because yours will probably break when you remove the cover

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Thank you for the vote of confidence. I removed the cover. The most noticeable difference between my mower and all the videos is my stuff is covered in oil. I figure that's fine?

I ordered the feeler gauge. And I'll work on getting the engine in the correct position tomorrow. The top valve does seem noticeably loose. And I did not break the cover.

There was also some oil on the spark plug which I think could be a problem.

StarTech said:

Then apparently the engine has been replace or you use a time machine to get the mower. The engine was built October 19th, 2012. So it is more likely you brought the mower in 2013.

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Let's keep the time machine thing between us. I just used it to get a new sales receipt. Adjusted to 2013.

Just that top rocker is the exhaust and lower one is the intake. Cross flow head design.

StarTech said:

Just that top rocker is the exhaust and lower one is the intake. Cross flow head design.

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I didn’t get back to it today but a puddle of oil leaked out the front of the mower over night. I think the whole problem may have been it being overfilled with oil… or perhaps a blown gasket.

I just need to get it to work one last time.

The mower is now leaking gas out the side of the carb. Doh.

I fixed the fuel leak and cleaned the spark plug. The mower still does not start. I tried cranking it with the rocker cover off and noticed oil coming out of the front. I don't think that's supposed to happen? I still think the problem may be too much oil remaining in the mower even though the oil level reads as normal.

StarTech said:

Just that top rocker is the exhaust and lower one is the intake. Cross flow head design.

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I believe both of these should be set to 0.005. The top rocker I can fit 0.009 into. The bottom one is good at 0.005.

Could that difference on the top one legit be the problem?

The rocker adjustment was a lot of fun and I did learn some stuff. But it did NOT fix the problem. All I can think of now is maybe drain the oil and start over?

I'm going to go buy some new gas, another new spark plug and get the battery charged back up. But at this point I'm grasping at straws. If anyone knows how to start a mower, now would be a good time

You need to figure out whether you have a fuel or spark problem. You need to purchase a can of carb cleaner and/or an inline spark tester. Both can be purchased at an auto parts store. Insert the spark tester into the plug connector and check to see if you have spark. If you have spark, remove the air cleaner and spray some cleaner into the air horn. Let us know what happens and we can go from there.

Rivets said:

You need to figure out whether you have a fuel or spark problem. You need to purchase a can of carb cleaner and/or an inline spark tester. Both can be purchased at an auto parts store. Insert the spark tester into the plug connector and check to see if you have spark. If you have spark, remove the air cleaner and spray some cleaner into the air horn. Let us know what happens and we can go from there.

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I did the carb cleaner already. The air horn is free and clear. I’ll look for a spark tester. I’m headed to autozone here soon.

Okay have the battery all charged up, new spark plug, new gasoline and an inline tester. Will report again soon.

Rivets said:

You need to figure out whether you have a fuel or spark problem. You need to purchase a can of carb cleaner and/or an inline spark tester. Both can be purchased at an auto parts store. Insert the spark tester into the plug connector and check to see if you have spark. If you have spark, remove the air cleaner and spray some cleaner into the air horn. Let us know what happens and we can go from there.

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We are getting zero light on that in line tester. I guess that means the spark plug does not fire. I feel like replacing the spark plug isn’t the anwser. So what do we do?

Unplug the kill wire from the coil and check for spark again. If no them take the coil off and clean the mounting areas on the coil and engine block. Have heard this all my life but only got it to work one time. But worth the try.

hlw49 said:

Unplug the kill wire from the coil and check for spark again. If no them take the coil off and clean the mounting areas on the coil and engine block. Have heard this all my life but only got it to work one time. But worth the try.

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No spark. In fact with that kill wire unplugged I barely get an effort out of the flywheel.

Here is what we are working with. I'm not sure if the big box stores sell a coil pack for my mower.

Any good repair shop should have that coil on hand. Part number 595304

I think that removing the kill switch thing wrecked the battery. We don't even get an attempt anymore.

One side of the underneath of the coil was extremely dirty. I don't think it matters though. The battery is now dead.

Rivets said:

Any good repair shop should have that coil on hand. Part number 595304

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Thanks. I think we are dead as the battery though. Lowes doesn't have it in stock and home depot doesn't appear to carry it. At 6pm on Friday, no small store is going to be open and both the small engine places here went out of business back in 2020/2021.

I ordered the coil. Thank you for the part number. That was a big help.

I'm going to take the battery back to autozone. It may be DOA now.

Four days... about 16 hours total. Mower no start.

Got another new battery and a new spark plug. Mower no start. I think the coil is bad. I ordered one and it will be here on Sunday.

When I do head gaskets & valve lash I raise the front of the mower about 6" to 1'
Even 4" ( a couple of house bricks ) under the front wheels will stop the oil making a mess
Noe if that oil is thin & smells like fuel then you have a carburettor float valve not working .
By the time you get done you will be ready to start posting you tube videos .
Do not get too prissy about the "tightness" of the feeler gauge
What I usually do is slip it in then tighten the gap so the gauge can not fall out then back off slowly till it slides out under the weight of the whole set .
Way back I was at an auto show where there was a competition stand where people could set a gap with a set of feelers which was then checked electronically
About 5% of the people who tried got it correct to within 0.0001 so went in the draw for a new car and less than 20% got it to within .0005" so got a pack of detailing products .

Stack223 said:

I think that removing the kill switch thing wrecked the battery. We don't even get an attempt anymore.

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Kill wire is a ground lead and is never connected to the battery
Cranking the engine is flattening the battery

bertsmobile1 said:

When I do head gaskets & valve lash I raise the front of the mower about 6" to 1'
Even 4" ( a couple of house bricks ) under the front wheels will stop the oil making a mess
Noe if that oil is thin & smells like fuel then you have a carburettor float valve not working .
By the time you get done you will be ready to start posting you tube videos .
Do not get too prissy about the "tightness" of the feeler gauge
What I usually do is slip it in then tighten the gap so the gauge can not fall out then back off slowly till it slides out under the weight of the whole set .
Way back I was at an auto show where there was a competition stand where people could set a gap with a set of feelers which was then checked electronically
About 5% of the people who tried got it correct to within 0.0001 so went in the draw for a new car and less than 20% got it to within .0005" so got a pack of detailing products .

Click to expand...

Thank you. I think the problem here is the ignition coil.

One of the rocker arms I could fit 0.009 in. I tightened it to where 0.005 fits and if I try really hard I can wedge 0.006 in there too.
The other rocker arm only 0.005 fit. So it seemed okay.

I'm on my second new battery now. The first one tested bad on my second trip to auto zone today. They replaced it under warranty. It was less than two weeks since I bought it.
I'm on my fourth spark plug. The original one went out in the trash. The second one is on the shelf. The third one I dropped and it shattered. The fourth one is in the mower.
I removed the carb, disassembled it and the interior was oddly very clean. The float is fine. I put it back together and didn't notice but I busted one of the screws in half. So it was constantly leaking gasoline. I fixed that today.

I bought the inline spark tester. Maybe it is DOA. Maybe I don't know how to use it. But with two different spark plugs and two different batteries, it doesn't do any kind of light show whatsoever. I removed the current coil and cleaned it. But that didn't help any. Nobody around here seems to carry the coil... websites say they can order it for $50. I bought one on amazon for $19... should be here for Sunday. Problem is that by Sunday my wife will have me renting a mower to cut the yard. This has been going on all week.

bertsmobile1 said:

Kill wire is a ground lead and is never connected to the battery
Cranking the engine is flattening the battery

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That battery is auto zone's problem now.

Oh I've also changed the oil three times this week... that's more than the past six years.

I had one of these, one day all of a sudden it wouldn't start, I checked for spark and there wasn't any. I did some research and found out that under the seat there's the usually safety switch which kills the ignition unless you sit on the seat but unbeknownst to probably most people, there's a secondary switch in the main switch that is meant to prevent someone from jumping the terminals and defeating the main switch, it's simple to change and that was the problem. The next thing that happened was the idle mixture solenoid on the bottom of the carburetor float bowl went preventing the engine from starting, two easy things to fix, one second they work and the next second they don't.

An internal comb. engine needs air, fuel, spark, and compression to start. Troubleshooting usually begins by testing for these. Changing oil will not cause an engine to not start, nor will improperly adjusted valves, unless they are so far out that you have no compression. When you adjust the valve clearance, you want the feeler gage to just slide in with no pressure - if you force the gage in, you are compressing the spring and setting the clearance improperly. I hate to say it, but you spent time changing the oil and adjusting the valves that was probably not needed.

Sears tractors have safety interlocks that prevent the mower from starting. It is usually easiest to test these switches with a continuity tester first. A wiring diagram is usually necessary to see what interlocks your mower has, but once located, it takes seconds to check. For example, my GT3000 has these safeties under the seat, on the brake lever and the mower/electric clutch. If the brake is not on or I'm not sitting on the seat, no start. Once you check these, move on to the next easiest item to check.

Spark. You can always check the spark by pulling the plug boot, putting a screw driver into the boot and laying the metal shank of the screwdriver on the engine. Crank it over and you should see a blue spark jump from the shank to the engine. DO NOT HOLD THE SCREWDRIVER, unless you like shocks. Alternatively, you could have removed the spark plug (blow air around the base to get rid of any dirt that would fall into the engine before you remove it), put the plug wire back on and lay the spark plug on the metal engine. Crank it over and you should see a blue spark at the tip. No spark is a problem. I think you found the cause of your non starting - coils do go bad. You will need the specs to properly position the new coil. Buying a spark plug tester is not needed.

Had you found a good blue spark, then the next thing to check would be the carb. Since this usually involves removing and cleaning delicate parts its not something that gets done first. If you start disassembling the carb, you will have to adjust the idle and full load rpm - not difficult, but more involved than, say, testing those interlock switches.

Thank you all. Unfortunately I don’t really understand this new advice. The ignition coil will be here Sunday. If that doesn’t fix it, I’ll probably just list the mower for $50 and be done with it.

I’m going to need to rent a mower to cut the grass.

Stack223 said:

Thank you all. Unfortunately I don’t really understand this new advice. The ignition coil will be here Sunday. If that doesn’t fix it, I’ll probably just list the mower for $50 and be done with it.

I’m going to need to rent a mower to cut the grass.

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It might not be more or not much more expensive to hire someone to cut your grass with their equipment, compared to renting a mower. There might be delivery and pickup charges with a rental that have to be added to the cost of rental and fuel cost as well. Then your time is worth something. Just a thought.

I didn't notice you saying you had spark. Remove the plug, hold it against the engine body with gloves or plyers and crank the engine. You should have a bright spark. Reinstall the plug, shoot some carb or break cleaner, or a shot of gas into the carb with the choke open. Turn the key and see if it fires. If so, you may just have a fuel\carb solenoid issue.

If no spark, with the engine cover removed, locate the ignition coil by the flywheel. Should be a small wire plugged into it. Unplug and check for spark again. Don't have, the possible bad coil. If there is spark, then there's probably a safety switch problem.

Freddie21 said:

I didn't notice you saying you had spark. Remove the plug, hold it against the engine body with gloves or plyers and crank the engine. You should have a bright spark. Reinstall the plug, shoot some carb or break cleaner, or a shot of gas into the carb with the choke open. Turn the key and see if it fires. If so, you may just have a fuel\carb solenoid issue.

If no spark, with the engine cover removed, locate the ignition coil by the flywheel. Should be a small wire plugged into it. Unplug and check for spark again. Don't have, the possible bad coil. If there is spark, then there's probably a safety switch problem.

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Yes. We did basically this yesterday. No spark with the inline tester. I removed the coil, cleaned it, reinstalled it. No spark. New plug. No spark.

New coil arrives tomorrow.

lbrac said:

It might not be more or not much more expensive to hire someone to cut your grass with their equipment, compared to renting a mower. There might be delivery and pickup charges with a rental that have to be added to the cost of rental and fuel cost as well. Then your time is worth something. Just a thought.

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Yeah. Hire is $150. Rent is $34.

Also did the small unplug of the coil. No spark that way either.

I noticed you got gasoline to the carb, but is the carb clean? Try to start with starter fluid, just a spritz, if it fires, clean the carb. Nine times out of ten that is why an engine won't run. Could check for spark. Fixing that is another issue. If the starter tries to turn the engine, but can't. That's a valve adjustment problem.

rhkraft said:

I noticed you got gasoline to the carb, but is the carb clean? Try to start with starter fluid, just a spritz, if it fires, clean the carb. Nine times out of ten that is why an engine won't run. Could check for spark. Fixing that is another issue. If the starter tries to turn the engine, but can't. That's a valve adjustment problem.

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I actually don’t know anything about starter fluid.

The carb was amazingly clean on the inside. Super crazy clean to the max.

The starter spins the center of the engine round and round very nicely. There is no spark from the spark plug. Tried three of them and broke a fourth by dropping it. No sparks.

looked up where to spray starter fluid. I could try that tomorrow. But don’t see how it would solve not having a spark from the spark plug. Don’t understand.

If you have no spark the suggestion of spraying starter fluid in is worthless. Don’t waste you money or efforts. I wish people would read the entire thread before throwing out answers like that, as they are wasting your time and $$$$$.

If you overfill with NEW OIL, and drain some out, the oil is REUSABLE. Don't overfill, and if you do, save it for next time. Also, do it more than every 4 years. Your 2012 mower is better than what you can buy today, so be good to it.

Mower now starts! However it shoots white smoke out of the area underneath the heat shield on the front. Takes less than a minute for the smoke. I think maybe it’s low on oil this time and not over?

I think the oil is low. The owners manual is extremely little help there as it says it could be 20 ounces, it could be 40 ounces. I think it’s 40.

The dip stick wants me to read it when it’s hot which is kind of hard to do when it smokes.

That part - lower front - under the heat shield smokes. I’m not sure what exactly it does. I’m also not sure if the smoke is just spilled oil burning off the outside or if it is interior related.

I am worried that I may have over tightened the rocker arm or something.

I think we broke it. No longer starts.

The engine kind of knocks now and then stops trying. Nevermind. Spark plug came unplugged.

We are back to the mower running but a little bit of white exhaust smoke. That may be normal. I don’t normally remove the cover and stare at the engine.

We did it! The grass is cut and the mower did not catch fire.

It did throw a spring though. I think this has something to do with the drive vs reverse because it would get very upset when I’d try to change.

Part number 20 on this diagram. https://www.partstree.com/models/24...n-tractor-2013/transmission-drive-assembly-9/

Rivets said:

Part number 20 on this diagram. https://www.partstree.com/models/24...n-tractor-2013/transmission-drive-assembly-9/

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Cool thank you. I think this is towards the front of the mower kind of directly over the deck. I’ll lift it up this week and take a look. That should not be hard to replace. Knowing the part is the hardest and you took care of that for me. Thank you.