For a more precise answer we need Make/Model/Year/Engine Model/Deck Size, and hours on meter if you have one.
Let's say you have less than 300 hours on the engine. Let's further assume it worked last summer, or last week, but now it's acting up. Let's also verify the battery is in good shape and fully charged.
A mechanically functional (meaning all the internal parts are working, i.e. pistons, valves, etc) engine requires 3 things, air, fuel, spark. So the quickest way to start your diagnostics is to remove the cover over the air filter and then remove the air filter. I do not recommend spraying Quick Start.
Removing the air filter and placing the throttle at full speed with no choke eliminates the "air" question. Dumping in the fuel eliminated all fuel related questions. What's left? Spark. If the engine fires and runs a bit, then dies, you have eliminated the spark question. The engine started so Spark and Air are good; you have to track down a fuel problem.
If the engine does not fire, you have eliminated the Air & Fuel questions; you must tract down a Spark problem.
Tracking down fuel problems.
Tracking down Spark problems.
If these simple steps do not solve the spark problem, you have a Spark problem that moves into the arena of complex. You will need to check coil gap and coil performance. If it still doesn't start you will need to diagnose the electrical system for wiring and safety switch problems, key switch problems, fuses, etc.
A Problem of Air Control.
If you determine the Spark & Fuel systems are good, the next likely problem is Valve adjustment out of wack. This is a problem of Air Control (and its sister compression), the third element in the engine trinity. Usually this problem shows up as backfire; either back through the carburetor or out through the exhaust. It will backfire while you are trying to start it. HOWEVER, it does not always generate backfire. You may instead notice that the engine spins more freely than usual; or oddly enough just the opposite and the engine bind while you are cranking it. This is because the compression is lost by out of wack valves or the compression is out of sync with the spark. You need a valve adjustment.
Once you get it running be sure to replace the Air Filter with a new one.
These simple steps solve most starting and running questions and problems.
Cranks no start ???
or no crank at all ???
2 different problems
but if it cranks, spray some carb cleaner in the air filter housing.
yes it starts ??? fuel problem
no ??? no spark
SOURCE: My 24hp Briggs and Stratton ohv engine has bent push rods.
unable to answer if valve opened or not but does sound like ur bottom valve is bent or piston made contact and bent it to fix need to remove head and replace valve also need to inspect piston face is not damaged from possible contact
SOURCE: hello i have a craftsman
It's sound like a fuel supply issue. If it has a fuel shut off solenoid in the carby, put your finger on it and check that it clicks when you turn the key from on to off. If not the solenoid is faulty or its not getting voltage from the key switch. Regards Phil
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