Mower With a Briggs & Stratton Engine Won't Start


I have a Briggs and Stratton 12hp engine in my ride on mower that will not start. I have replaced the battery and starter, and have cleaned the carburetor. The engine turns over slowly as if the battery is low on charge (although I have charged it up) and there is a good spark at the plug. I have tried jump leads off the car, but it does not help. Any ideas?

By gd21 from Sunshine Coast, Qld


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By poutokaipara 3 04/06/2011

Go to youtube type in cant start whatever model mower wont start and lots of videos will show you how to. All kinds of mowers. No harm in trying.

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By poutokaipara 3 04/06/2011

Also it might not be earthing properly when you replaced the starter motor and battery.

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Archive: Mower with a Briggs & Stratton Engine Won't Start

My mower with a B&S (Briggs & Stratton) engine won't start. Per feedback from others concerning similar problems, I took plug out still attached to wire, there was no spark when I pulled cord. The plug snapped in so it had a good connection. The first time I pulled, my wife said it shocked her, but no spark. (Holding it in the wrong place?) After that, nothing. It was daylight and in the shade, would we see a spark? Also, a couple of weeks ago it started fine with the old gas still in it. Then I changed the plug, filter, oil and blade. I didn't change the gas, but I did add new gas. I also rinsed it off with a hose pretty thoroughly. Any of this give anyone any ideas? I'd appreciate any tips. Terry from Charleston, SC

RE: Mower with a Briggs & Stratton Engine Won't Start

If you washed the motor, it sounds as if you have water in the gas. Take the bowl off at the carburetor, and see if there is any water in it. Pinch the fuel line off so you don't have a gas spill. If there is water in the gas, drain it out and try some new gas. (04/13/2006)

By Tom Mann.

RE: Mower with a Briggs & Stratton Engine Won't Start

I would also dry out the fuel tank and refuel with fresh gas. BUT... I just bought a new push mower with a Brigs and Stratton motor last year from Walmart. And once the fuel gets down to a quarter of a tank or less, it will not pick it up to start no matter how many times you push the bulb to prime it. You may need to simply add more gas. Hope this helps. Sherry (04/13/2006)

By Sherry Nelson

RE: Mower with a Briggs & Stratton Engine Won't Start

As others have mention I would clean gas out of the carburetor and fuel line. Onetime I added a stabilizer product to my gas in my mower and let it sit over the winter.In the spring the gas had turned to a jelly consistency.Had to clean fuel lines and carb.Started fine after that with new gas. (04/14/2006)

By Dean

RE: Mower with a Briggs & Stratton Engine Won't Start

Thanks for the feedback, but it still won't start. I've drained all the gas out as best as I know how. (Just took the bowl off the bottom of the carb.) I even went and got new gas, still no luck. By the way, I do have a spark, so it's not the plug. I put a little gas in the plug hole and it tried to start for a second or two, but that's all. Is it time to replace the carb? Is that something anybody can do? Is it time to take it to a repairman? Help! (04/14/2006)

By Terry

RE: Mower with a Briggs & Stratton Engine Won't Start

Mystery solved. It was a gasket. A gasket! All that trouble. Thanks for the help. (04/15/2006)

By Terry

RE: Mower with a Briggs & Stratton Engine Won't Start

It sounds like the ignition wire has a short in it. You may have to replace the magneto coil and wire. It is located under the engine's top shroud. (10/06/2007)

By Ernie

RE: Mower with a Briggs & Stratton Engine Won't Start

The Spark Plug needs to be grounded to the block. I use insulated pliers or gloves and hold the spark with wire attached, plug to the engine block. I would imagine it is getting a spark if there was a shock involved.

It may have water condensation in the gas tank / line. If it has water in the gas line or tank, you can take it to a repair shop and they will do it in within 30 minutes time for typically 50-80 bucks, or do it yourself. I was told water in tank or gas line was not a covered warranty issue.

I read on another site (do at your own risk):

1. remove the gas line from the gas tank and have container to catch the gas coming out. You may need two containers. One to catch the gas thats coming out and another, larger container to dump the gas into.

2. Once tank and line is empty, locate the carburetor bell housing. On a Briggs and Stratton engine, it looks like a silver bell. There is a 1/2" size nut at the bottom. LOOSEN, but dont take apart, and let the gas leak out, mine only leaked out 3-4 tablespoons of liquid. Once it stops dripping ( 3 minutes or less) , tighten bolt and put all gas lines back on.

3. Clean up excess gas spillings, and add more known good gas in tank, and about 1/4 or less of dry gas or carb cleaner. Apparently Lowes sells a product that helps remove water out of gas mower tanks better than Isopropyl Alcohol.

4. If accessible, I removed the air filter and had a folded napkin ready to help block that hole . I had my son try starting the engine, and it started, and I used the napkin to block air flow. It helped suck out all air and water out of the mower. Just before it was ready to stall, I took napkin off hole. If mower stalls, start it again, use napkin as necessary, repeat again until it it runs normally. Only had to use napkin twice.

Make sure your gas is good, it can be cheap unleaded, and it should work fine. if it doesn't it either has a Boatload of water in the machine, or thats not the probem.

Hopefully this helps and makes sense. (11/07/2007)

By major tom

Archive: Mower with a Briggs & Stratton Engine Won't Start

I'm working on a 12Hp Briggs which powers a ride on mower. It won't start and a compression test revealed it had only 7psi dry and 10psi wet. I've stripped the engine bare and can't find a single thing wrong with it. The engine has completed perhaps 100 hrs. Everything inside the engine is as it should be. It has electric start, so I would have expected more than this small amount. Has anyone any idea what the compression pressure should be?

David from England, UK

RE: Mower with a Briggs & Stratton Engine Won't Start

The Briggs with next to no compression, we found the fault in the end. Careful (very careful) inspection of the cylinder head revealed a burn mark where gas had been leaking past the gasket. Obviously very little was leaking past but on reassembly of the engine, cleaning the carb, changing the fuel and basically doing everything we could think of, she starts and runs fine. Hopefully this info will help some of you other guys out there with similar problems. (04/25/2008)

By studentbiggles

RE: Mower with a Briggs & Stratton Engine Won't Start

Should be around 60-80psi. (06/01/2008)

By Chris

Archive: Mower With a Briggs & Stratton Engine Won't Start

I have a Briggs and Stratton riding lawn mower, Model 42A707. I just replaced the battery. When I turn the key, you can hear the starter spinning...


Archive: Mower With a Briggs & Stratton Engine Won't Start

I have a 14hp Briggs engine on my lawn tractor. It will not start, it has no spark, and has plenty of gas. I have checked all of the safety switches. I have actually jumped them out and still no spark. Where else can I look?

By skynyrd57 from PA

RE: Mower With a Briggs & Stratton Engine Won't Start

For those who can't get a spark; Did you make the sure the spark plug is clean - that the electrodes are not corroded or clogged with soot or oil? Also, when you tested for a spark, did you make sure the earth electrode was firmly pushed against part of the engine casing that was bare metal? If both of these are yes, then the next place to look is the coil that fires the spark plug. Use a multimeter to check that all the coils are okay. (05/18/2009)

By alloydog

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