i release the brake it cuts off….I have replacer the relay and the saftey switch…Did not help at all.. I even jumped across the seat switch…Not help…
20 hp 42 in. Deck Lawn Tractor – CA Model

Experienced gardeners share their insights in answering this question :
Check to see if the 20 amp fuse is blown if so replace it & see what happens

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If you pull the cord and hear your engine turn over, but your mower is not starting, the most common reasons for this are low fuel, a broken gas valve, or a bad choke fault. A broker spark plug could also be the culprit. You may also have to change the fuel pump if it does not get fuel to the ignition system.
Some of the B&S auto choke carburetors tend to supply too much fuel to the cylinder when hot starting; this floods the spark plug, causing a no start. They have since modified the carburetor. So if you have an auto choke, Briggs, with the hot start problem, go ahead and swap out the carburetor.
A Dirty Carburetor Can Cause a Lawnmower To Start Then Die

By far, the most common issue that causes a stalled motor is a dirty carburetor. The carburetor on your engine is the thing that draws in air and mixes it with the fuel. Contrary to what the movies might make you think, gasoline itself is not very flammable.

Whenever the blade is engaged, it rotates on a crankshaft to cut the grass. But if there is interference in this rotation, the engine can overload and shut off or lose power. Check the crankshaft connection to see if it rotates freely. Inspect the connecting hardware for damage or rust.
Loose, Dirty or Disconnected Spark Plug in Your Lawn Mower: Check it out, clean off debris, re-connect and tighten. Dirty Air Filter: Clean or replace. Fuel Not Reaching the Engine: Tap the side of the carburetor to help the flow of gas. If this doesn`t work, you might need a new fuel filter.
Check the Battery

The battery is the next stop when investigating a slow cranking mower. A weak battery cannot sustain enough charge to spin the starter mower and turn the mower`s crankshaft. Mower batteries last around four years, so one that is older may be ready for replacement.

Clip one end of a spark tester to the ignition cable and ground other end to the cylinder head. Spin the flywheel rapidly (at least 350 RPM) and watch for a spark in the tester window. If there`s no spark the coil will need replaced.
If no spark appears, check for broken wires, shorts, grounds or a defective stop switch. Once you have confirmed that the stop switch is working, reconnect the spark plug lead. If your ignition start or push button start needs replacing, consult a Briggs & Stratton dealer near you.
Use Carburetor Cleaner

Fortunately, you can generally do this without even taking the carburetor out of the engine. Start by purchasing some commercial lawnmower carburetor cleanerOpens a new window, which comes in a simple spray can and will make it easy to clean the inside and outside of the carb.

Your lawn mower runs for 30 minutes then dies if you are having issues such as a bad spark plug, air problems, a malfunctioning carburetor, or a faulty gas cap. You may even encounter the issue that your lawn mower runs for 5 minutes then dies.
The most common reason your car starts then dies immediately is because of a lack of fuel in the engine. This often happens because there is a small amount of fuel in the fuel rail, which helps to start the engine. However, there is no fuel pressure to keep the engine running.

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My lownmower will start and run only a min. and cut off…If I hot wire the switch on the bottom of the carb it will run great..But as soon as i release the brake it cuts off….I have replacer the relay and the saftey switch…Did not help at all.. I even jumped across the seat switch…Not help…
ANSWER : Check to see if the 20 amp fuse is blown if so replace it & see what happens

Cranks up and runs fine ,then starts cutting out then runs fine and starts cutting out again
ANSWER : I am no pro but my suggestion to you is if you have changed your spark plug recently check the gap on it and make sure it is right and make sure is the right spark plug for it. Also check the oil if it is low the motor as it gets hot will start to sputter or if it has to much oil it will have an air lock and blow you Lhead gasket after a while. Another thing to check is the air filter to make sure it is clean and check the timing with this if you don’t trust your self ask an repair expert for your brand of mower.

I have a husqvarna 323L string trimmer. I stored it after running the tank & carb dry for about two years. I fueled it, then started it, & it ran for a minute then died like I turned the switch off. Since it would not restart, I found the fuel filter had broken off the hardened fuel line & it sucked gummy crap out of the tank & into the carb. Failing at cleaning the carb, I finally put a new carb on it & replaced the pump, hoses & filter. It has ran good till this year. I winterized it with stabilizer & left it with a full tank over the winter. The gas in the tank was gone when I got ready to use it this year. I filled the tank with premix, checked for leaks, then started it. It would run fine for about half a tank, start idling poorly (lean) then cutoff & refuse to restart till I refilled the tank. I finally found the tank had cracks & was letting pressure out of the tank & apparently this was causing the carb to lose it’s ability to siphon gas out of the tank. So I replaced the tank which came with new hoses & a filter, which I properly installed to the carb. It cranked right up, but when it runs a half tank, the carb quits sucking gas out of the tank. When I pump to prime the carb, it moves the fuel into the carb, but the pump never gets hard like it does when I prime the carb when the motor is cold. I have to keep refilling the tank, prime, & then it starts & runs until the tank gets about half empty. The new fuel filter is down in the gas tank properly, but It will not run after it shuts off until I refill the tank & prime. I’m baffled. New tank, new hoses, new filter, new carb, & I can find no leaks in the fuel system. It runs strong. The 323L is a two-stroke & it always cranks on the second pull from cold on a full tank. Any ideas?
ANSWER :

Self propelled mower will start but want stay running long? it runs about 3 or 4 min. then stop and when i restart it, it will start back up.
ANSWER : The fuel bowl has a float and needle, if the float isn’t floating to open the needle for gas to flow into the carb, it will cut off. A kit can be purchased for about $5 or take yours out and soak and clean then replace. Usually when these go bad its best to replace them.

When I let the cluth brake out my engine shuts off
ANSWER : Sound like 1 of your safety switches is bad. mower will run with the brake on and your not on it. there should be a seat switch under the seat, there should be a blade engage switch somewhere on the chassis, and there is also a brake switch. trace your wire harness through out the mower and check each switch. you can check the switches by unplugging them and connecting a wire to each terminal in the plug to check each 1. if after you unplug a switch and use the wire and the mower stays running after you release the brake then that switch is bad….you can bypass the switches by leaving the wire connected to the plug.

Parking brake wont release on a 310e back hoe, replaced the parking brake switch and that was no help
ANSWER : Sounds like the whole stop brake system is seized up. Lot of wd40 and elbow grease should do it.Good luck.

It starts and runs for a bit but as soon as it hits thicker grass it dies
ANSWER : Joe Hi there. Sadly your trimmer will struggle on thick grass as it’s not made for it. You could try moving the trimmer like a scythe. This will aid it as your cutting bit by bit.

My Husqvarna mower starts right up but when i release the emergency brake before starting the blade it shuts down automatically.
ANSWER : You need to check the safety switches bypass them one at a time to find the bad one