Ariens Briggs & Stratton won't start.

[Ronni]

Have you tried more "starter fluid" while starting?

 

[riceski@gmail.com]

Usually when a flywheel key shears from hitting a rock or whatever the engine stops immediately and you know what you hit, but I once had one that had apparently sheared previously but the flywheel didn't move enough at the time to notice. It later shifted from nothing but heavy grass that couldn't have sheared the key. But usually when an engine stops abruptly, it's lack of spark or fuel or (N/A for this case) a thrown rod or broken timing belt.

I use a timing light for spark detection, it's pretty reliable and lots more fun than just grabbing the plug contact.

I agree - timing. Spark is there - just not when both valves are closed. Weak coils also - coils are mostly cheap now. REPLACE also think about replacing the keyway on the crank-flywheel

 

[Richard Milhous]

I agree - timing. Spark is there - just not when both valves are closed. Weak coils also - coils are mostly cheap now. REPLACE also think about replacing the keyway on the crank-flywheel

The OP (who seems to have given up on this thread) said the flywheel key was good.

 

[D_H]

The engine will not fire with a fuel that is far more volatile than petrol put into the combustion chamber through the plug hole.
So that tells us you have a valve / piston problem.
So next step in diagnosing is to put a pencil down the plug hole and check that there is a piston in there that is moving .

No, I had not done that yet. I sprayed carburetor cleaner down the air inlet to the carb with no effect.

Ariens Briggs & Stratton won't start.

I need help. I have an Ariens 20 horse 46" riding mower from 2012. It's ran like a champ ever since I bought it new. Now, I started it up, pulled out of the garage and it died while I was driving it out of the garage and off the driveway and will not start back up. Mower info: Ariens: A20H46...

www.lawnmowerforum.com

I have now taken the spark plug off and sprayed carb cleaner into the spark plug hole, assembled the spark plug back into the engine and attached the spark plug boot. I turned the engine over and the engine tried to start ever so briefly.

When I had the spark plug out, I placed a straw down the spark plug hole and turned the flywheel a few times. the straw moved in and out of the opening accordingly.

Visibly that will check for spark. But is it enough to fire across the gap under compression? No way of telling with a timing light.

Either gap a plug to 1/4" or 6mm or get a real tester like the one below.

I got a new spark plug and opened the gap up to 1/4". I had to bend the post all the way straight out to do that, with a slight bend over to center. I placed the spark plug in the boot and rested the tip of the spark plug on a frame bolt. I could see spark a few times when the engine turned over, but only a few times. Most of the time the engine turned over, no spark.

Additionally, when the engine turned over, the compression shot fuel out of the spark plug hole about 3 feet. There is a mist, quite a few droplets, and almost, borderline a spray, especially on the first revolution.

Try pinching off the fuel line while cranking. Wondering if the cylinders are flooding as in carb needle sticking open?? Remove the plugs to clear and dry out the cylinders while cranking.

I did this with no effect.

Best never to use ethanol gas in anything. Ethanol absorbs water, and the underground gas tanks at stations often have leaks. With straight gas, the water settles to the sump at the bottom and is unlikely to get pumped out. Ethanol diffuses the water all through the underground tank. I have a suspicion this is why so many people report lousy gas mileage with gasahol - the difference in energy content between gasahol and straight gas is only 4%, but add a little water and you've got a problem.

Got it, nothing likes ethanol, vehicle engines, small engines. It's crap, agreed. The only way I can get pure gas is to travel about 300 miles to a gas station that sells it. Not going to happen. I mowed with it last week and the week before that, etc on the same gas. 87 octane always.

I predict this is the Solution. Always keep the tank Full. In hot ,Humid weather a near empty tank causes Condensation. Your Gas is Bad. You have Spark and Compression. Remove plug and blow out all bad gas and let it sit with plug out for 15-30 minutes. pour a glurp of gas in carb throat and Start engine.

The tank has never been below 1/4 tank since I first ran it in 2012, most of the time the lowest it gets is 1/2 tank. I'm in Texas, it's hot all year, except for about two days for winter.

Sorry to hear you have having problem with the BS. My 50 year old B&S quit, and it was just the spacing between the coil and flywheel. The spark was weak. I found there was nearly no gap. I loosened up the coil, slipped a business card in, to make about a .020" gap, tightened, and bingo - hot spark, and engine running like new. It can sure be a lot of little things. Let us know what you find D H

I took off the ignition coil/magneto to clean the fly wheel a little and also the ends of the ignition coil. I placed it back on and gapped it to .011. No change. I've tried to find a replacement ignition coil, but the ones I find appear different. Different design, with a 45 degree spark plug boot. the stock ignition coil has a straight boot and the coil itself looks different.

The OEM ignition coil appears to look like this one below with the exception of the contact connector to the spark plug on the OEM has a straight connector, this one in the picture below has a 90 degree connector.



This is what the replacement ignition coil looks like. I looked it up for my engine.


If click the link or go over to page one you can kind of see the ignition coil there.

Ariens Briggs & Stratton won't start.

I need help. I have an Ariens 20 horse 46" riding mower from 2012. It's ran like a champ ever since I bought it new. Now, I started it up, pulled out of the garage and it died while I was driving it out of the garage and off the driveway and will not start back up. Mower info: Ariens: A20H46...

www.lawnmowerforum.com

 

[D_H]

Have you tried more "starter fluid" while starting?

Yes, no effect.

I agree - timing. Spark is there - just not when both valves are closed. Weak coils also - coils are mostly cheap now. REPLACE also think about replacing the keyway on the crank-flywheel

Ariens Briggs & Stratton won't start.

What type of inline tester is this? One with a simple light inside? If so toss it in the trash. You should test the coil under LOAD. Gap an old plug to 1/4" or 6mm. Ground it out and check for spark. Some carbs have a pilot jet on top that you can see from the outside of the carb. If yours has...

www.lawnmowerforum.com

 

[D_H]

Don't highjack my thread and turn it into an ethanol, stabil, winterizing practices discussion. There isn't any non ethanol fuel anywhere around me, if there was I'd be using it in everything I have that runs. I'm in Texas, it's hot all of the time except for about 2 days in winter. The mower sits for about 2 1/2, 3 months when the grass is not growing in the winter. The gas tank is always at least 1/2 full.

I want to provide this for what it's worth. I have never changed the oil or filter on the mower until this year 2021 in February at the beginning of this mowing season, remember I bought it new in 2012. I have checked the oil over the years periodically before I would mow. The oil was still amber color and at the correct level when I changed it finally a few months ago.

So next step in diagnosing is to put a pencil down the plug hole and check that there is a piston in there that is moving .
Once you have confirmed that take off the rocker cover & spark plug
rotate the engine at least 2 full rotations while watching the rockers moving
The valves & guides are identical so they should sit at exactly the same height and go in & out the exact same amount
When the piston is in the firing position both vlaves should be closed and there should be some slack between the ends of the rockers & the top of the valve stem.

When I put a straw into the spark plug hole and rotated the engine to check for movement, I kept slight pressure on the straw while turning the flywheel so it would stay pressed up against the piston while it moved. The straw slid across the top of the piston a few times as it would rotate. I could feel it do that with my hand. Then when I pulled the straw out, I noticed there was some black sludge on the tip of the straw. Oil build up I guess.

Just to review, I mowed with it for a long time on the same oil and filter, I finally decided to change the oil, oil filter, spark plug this year. I could not find the B&S SAE30 at the time but I did find 5w30 synthetic, the manual said that would be just fine, so that is what I used. I've been mowing with it over the summer this year just fine up until a week ago. I have checked the oil level every time I mowed this year. I have noticed that the oil is being consumed almost every time I mow. The level drops from each mow, just a little. The oil is also black now.

Things I've done since it died.

• Put a new spark plug in it. [(Calls for Champion# RC12YC - obsolete) compatible NGK - BKR5E. 7938 is what I used.] I also found and bought Briggs & Stratton 5092 PN: 496018S.
• Changed the oil and filter. (Briggs & Stratton oil PN: 100028, filter calls for B&S 492932 - obsolete, I used B&S PN: 842921.)

Question: When you try to crank the mower and it doesn't crank, is the spark plug wet or dry? You tried starting fluid. If the plug is firing, the engine should do something if nothing but sputter. If the plug isn't getting wet, then the carb is stopped up. But one thing that puzzles me is that you tried the starting fluid, (ether), and it doesn't do anything. If the plug is good and shows fire, the engine should do something.

When I remove the spark plug, it has some fuel on it. It is beading around the conductor and I also see it in the threads. I can smell the gas on the spark plug.

I appreciate all of the helpful input!!!! You guys are helping me and anyone else that might follow.

After the information I've provided:

• Are you guys thinking that I have a carburetor issue?
• Still think my ignition coil is bad?
• Based on what I said, do you feel I have good compression?
• What are your thoughts on the oil use, buildup inside the piston? Sounds serious.?
• Any thoughts on the positive crankcase ventilation (PCV valve) AKA crankcase valve being clogged? I have not had any performance issues that I can tell of.

 

[bertsmobile1]

If the engine actually goes bang with spray down the plug hole & not with spray down the carb that suggests the inlet valve is not opening.
So take the rocker cover off & check the valve lash
rotate the engine by hand, plug removed.
Both valves are identical and positioned identically in the head so should move the same amount and sit at the same heights fully in & fully out .

 

[hlw49]

Do not ever use starting fluid in a small engine had a guy burst a head using it. Buy the cheap Gum Out carb cleaner it will not hurt the engine. I drive them in the shop using it. In line test light spark testers will not always give you a true spark reading it takes very little voltage to light them. Use the gap type to test the spark it simulates the spark under compression. As per Briggs, Kawasaki and Kohler.

 

[ccheatha]

Do not ever use starting fluid in a small engine had a guy burst a head using it. Buy the cheap Gum Out carb cleaner it will not hurt the engine. I drive them in the shop using it. In line test light spark testers will not always give you a true spark reading it takes very little voltage to light them. Use the gap type to test the spark it simulates the spark under compression. As per Briggs, Kawasaki and Kohler.

I hear people say that a lot. I've used starter fluid on many engines and never had a problem. For me, it's a last resort after trying any number of other things. If the engine will not start without it, that's an indication that something else is wrong anyway, I suppose. For me, it's a quick test to see if the engine will actually fire - even if it dies shortly after. If it fires once, that's all I have to know and then I can just figure out why gas isn't making its way in. The biggest problem is that a lot of people don't understand that it should be used in moderation; give it a quick squirt and try to start it - don't spray half a freakin' can down the hole.

 

[snl]

Have you verified that you don't have water in the gas? I had a Honda mower that always ran great. It was almost out of gas when I put it away and refilled it with new gas when I went to use it again the next week. It cranked up and ran good for about 30 seconds and then died. It wouldn't start again till I drained the carburetor and tank. After letting the gas settle I could see that the new gas was full of water.