I have one that starts fine. At low throttle, it runs fine. As you throttle it up, it pops and backfires through the carb. New carb, intake, coil, plug, fuel filter, and fresh gas
Cannot diagnose without seeing the machine but a guess would be You could have a bad new carburetor. OEM is the way to go. I haven’t had much luck with the aftermarket Briggs carburetors on the single cylinder or twin engines. Or it sounds like valves issues or a possible slightly sheared flywheel key. Most likely a sheared flywheel key will pop and miss all of the time and you said it runs good at idle. Check spark plug gap is at .030”
Dealing with popping & missing myself on a 20hp at high rpm. Lash was so loose both pushrods fell out & bent. Replaced those, lash set on both cylinders, cleaned the carb, new plugs, air gap on coils set, all new fuel lines with filter, new air filter/pre filter. I'm pissed off at this point because I'm a mechanic. No visible damage to the head from the pushrods. I'm starting to think a failing coil when hot. They ohm out when cold. Fuel regulator can't be an issue because the filter stays primed.
I’m glad all worked out and you’re back up and running! Thank you for the kind comment. Please give this video alike and share my channel to help it grow. It would be greatly appreciated!
Saw this exact same issue on another channel. Was the same mower too. Seems that stud problem is a real issue with this mower. The other engine had a valve rotater that fell off but was contained by the valve cover. Good vid, thumbs up.
I've seen where the keeper for one valve was not present on diagnosis and disassembly. It was not found either. One was obtained from a donor mower with a bent crank. Not made in USA and it shows.
found this video from your recommendation to me on another of your videos. my rocker arm was identical to this, extremely loose, i took the head off and the valve seat was displaced with the valve stuck on it. also the head-gasket was blown in the typical spot. But my engine is a Briggs & Stratton 18hp OHV Intek, known for blown head - gaskets. I did notice that there are stress fractures in the aluminum on the inside but not on the smooth part of the aluminum where the head gasket sits. It's inside on the intake side, multiple stress marks/cracks. I think i'm good on that but i'm not a metallurgist and i figure you have seen that on these B&S aluminum heads more than once and I value your opinion....THANKS.
I have the same mower. Was working fine before. Today, I started it and didn't move the handle from Choke to Run in time. The engine stalled. Now trying to start and what I get - very loud pops. Tried twice. I guess I'll let it sit overnight and try tomorrow. I'm not knowledgeable when it comes to engines.
Hi Wayne, I'm glad it was helpful and thank you for the kind comment. Please give this video a like, subscribe and tell your friends about my channel to help it grow. It would be greatly appreciated.
Mine was doing it when it was running i traced it back to one of the spade connectors on one of the coils it wasn't loose enough to fall off but the vibration of the engine would cause it to lose connection while running.
Great explanation and concise . I was looking for something different but decided to watch this anyways and learned something . I'm wondering if that stud had any loctite to begin with .I've had unpleasant surprises before like four bolts on a steering column in my Pontiac that should of had it from the factory but didn't and backed out . So much fun 👍... NOT !! 😹
I still don't know how this happens to people, poor maintenance but after 260hrs and only oil change i still had factory valve clearance not to say i didn't have other problems but was a flow on effect from poor ignition
Thanks Logan, I’m glad it was helpful. Please give this video a thumbs thumbs up, subscribe and tell your friends to help my channel grow. It would be greatly appreciated:) thank you for watching
I’m glad it was helpful and thank you for the kind comment. Please give this video a like, subscribe and tell your friends about my channel to help it grow. It would be greatly appreciated. Thank you for watching.
Sometimes a weak spring will cause it. And like he said look for the wear caps that fit over the end of the valve. Some motors have them some don't. They look like a watch battery hollowed out on one side.
@@danielrisnes3117 Most likely a carburetor jet or fuel supply partial blockage (dirty carb jets, fuel filter, pinched fuel line, etc) causing it to run lean. This causes lack of power under load (slowing down) and lean misfire (popping). Is still possible to be an a rich misfire (spark plug and muffler outlet will be really sooty), ignition timing or valve issue but much less likely.
Hi Brad. I have a lawn mower with a Kohler 775 and I hitted a rock. The piece of metal that hangs the blade to the camshaft broke, but, after that, the engine started to pop and miss. I thought it was the flywheel key, but it´s OK. The spark plug is OK also. I don´t see any leaks and the camshaft is perfectly alined. What do you think it could be? Thanks!!
I will assume that you mean 7.75 hp. Normally, it’s just a sheer flywheel key. Will it run? I don’t work on those engines any longer, so I do not know of that engine type. Without seeing the machine and listening to it. Impossible to diagnose. You may have heard the internal parts of the engine? Just guessing.
Both, it is pop and missing and will not start. If your engine is running popping and missing but you are able to use the machine, you have other issues like possibly a bad carburetor or bad spark plug.
Wife was mowing w 2016 last year, cutting w mowing deck on 1, said it quit on it's own , last year. Finished the season w push mower. The flywheel fan broke in half, looked melted, got plug wire. Replaced magneto & fan assy, cleaned fuel bowl , repl fuel & filter, spark plug. Backfires out exhaust. I'm pulling the valve cover, any other suggestions??
Hiya. I have a briggs and Stratton quantum self propelled mower. It ran out of oil popped now won’t start. Just pops . It has compression as I can pull cord with tension, any ideas as I can’t afford a mechanic . Thanks
Running it out of oil definitely hurt the engine. From what you have told me, my guess would be either a sheared flywheel key or valve issues. I do not have any videos on those issues for walk behind lawn mowers.
What's the purpose of the selonoid? Engine, 19.5 HP, slowly fowled plug. Mines not clicking. After I made sure valves were right, keyway was fine, was getting gas, great spark, little over 60lbs cylinder pressure just wouldn't start back up. Guess I'll try that, ran fine all season...
It sounds like you may have a low battery charge or a safety switch not working if you are not hearing a click. The purpose of the starter solenoid is when you turn the key to crank, the key switch sends power to the solenoid and then the solenoid inside throws a magnetic to the other side making contact internally to send power to the starter to make it crank the engine. Normally when solenoids fail, you will hear a click inside the solenoid but the starter will not crank because the magnetic in the solenoid is stuck. Then replacing if the solenoid will be needed.
Was the selonoid under the carb, had 10hrs on it. I cut the plunger off and added a petcock on fuel line, runs better than before. A .50cent part from china probably.
So how do you do the rest of it then? Do you need to have measuring shims to tighten it down a certain amount? My mower has started popping/backfiring especially when hitting bumps, almost stalls out sometimes. Replaced the spark plug, air filter, and checked the flywheel key. Was going to test magneto but supposedly checking the ohms is pointless.
@@JohnsonsSmallEngines Adjusted valves, fuel filter, cleaned out carburetor... Ended up being my damn seat safety switch. I ended up testing that out because sometimes it would nearly stall when turning. At least I know my hog is in tip top shape 8)
Mine dose something similar but when it's running it dose it. But when it heats up it stops. And sometimes when I shut it off it makes a really loud pop. When I started it up one day it popped and I think smoke came from the carb. If anyone knows what it means please let me know.
It sounds like you may have one of several issues, you could have a failing ignition coil or a clogged fuel cap making it stop when your running it. Does the engine run good until it stops? then after letting the machine sit for a while will it restart?
The motor fires up every time but once it's sat for 3 hours or so when you start it back up and it pops but then when when it's ran for 1 minute it runs great. But every now and then when you shut it off it makes a super loud pop like a gun shot.
That is a little tough not hearing it and not knowing background on the engine, If it is a twin cylinder? Need to know how many hours you may think is on the engine? Any issues with mice in the engine? If yes, could be valves. The twin Briggs also had issues with a plastic intake manifold and poor quality gaskets from intake to engine which could also make a miss or pop. It could also be a little dirt in the carburetor. This is only if your engine is a Twin cylinder Briggs and Stratton.
@@JohnsonsSmallEngines it’s a bs v twin 22hp, 110 hours, may have issues with mice? Thank you very much for your quick response, it’s greatly appreciated. How do I check valves? Also could it be a coil?
I would first replace the intake gaskets to see if it gets better. Briggs part # 594209. They come in a two pack. Much easier to install. If the engine overheated due to mice I would first adjust the valves and unfortunately I do not have a video on adjusting a twin cylinder Briggs and Stratton yet. Somebody may have something on it. An overheating issue is not good as you may have valve seat issues after the valve adjustment doesn’t work. The only way to check that would be to take apart the engine and I would not recommend that for a back fire every now and then. Try Installing the Briggs intake gaskets if you can find a video on that. I do not have one yet. I will at some point but need the machines to come into the shop with the issue to make that happen.