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I have a 12 year old 19.5 hp craftesmen riding lawn mower that runs at high and low ideal when no blades are engaged but now when i engage the blades the motor stops running. Changed oil,changed plugs ,changed air filter,washed ,air tires. No luck fixing.
Turn your mower off and check how the blades turn underneath the deck. Any obstruction, damaged pulley shaft, or seized pulley can be the cause of that. Check your belt and make sure it is properly routed and that it does not get hang up at at of the belt guides. Remove the pulley covers from the top of the deck, and check to make sure that he belt and pulleys are properly functioning. I also think that there is a possibility that your mower may have a safety interlock system that prevents the mower from engaging when there is no operator. So check on the safety switches, I believe it to be on the seat. as well as on the parking brake. This of course is only valid if your engine is properly running, that the idle is high enough and that the engine still has enough torque to deal with the mower deck. Good Luck and I hope this helps.
Definitely check wiring and all switches, starting from the ignition switch, behind the panel. Occasionally over the past year my John Deere Sabre would be difficult to start, and more recently every time I would fully engage the PTO lever for the mower deck, the engine would die. $500 in parts and labor later (carb, plugs, fuel pump, fuel filter, battery) I discovered that the wiring harness/plug behind the key on/off switch was loose. When bumped slightly by the PTO lever engaged, it would loosen and engine would not restart until the loose switch/plug settled back into place temporarily. Another sign that it was loose wiring or a switch should have been that sometimes the engine would die while rattling around over a bump, even without the PTO lever engaged.
Had same problem with my Hustler Fastrak. After cleaning carb, changing fuel filter, air filter spark plugs I still had the problem. I realized that it only stalled under a load. I decided it was a weak fuel pump. After replacing the fuel pump it works like a champ. Probably needed to do all the other things anyway. Hope this helps.
I find it to be the safety switches being the culpret, check for out of positition, debries interfering with it, its not nessarily the switch , the can be pricey. if certain conditions are not met, trying to engauge the blades will cause the engine to die.
When I had this problem, the engine only stalled when cold. It turns out the problem was a blown head gasket (a common problem with a Briggs and Stratton engines)
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When the mower deck safety switch is working correctly - you can engage the blades and the mower will not die. Well if that switch isn’t getting pressed or depressed correctly by a rotating piece of metal connected to the engage wire or in my case, it’s all metal pieces - I have a SABRE and there’s a rod with a spring on it - that rod that goes through the spring will get out of circle and wear out to an oval shape. well there’s a shape like this [______] now imagine a spring and washers on the inside of that on both sides - well how the bar stays inside of that - there is two little bumps - well once that metal bracket thing is worn to an oval that bar will go right through - so there is NO spring action - that spring action is just enough to put pressure on the switch - when there’s no spring action, that switch can not get pressed. When you go to start the blades and your mower is running fine but it dies when you start them - that button is not getting pressed in all the way - due to that slack - and it will kill the engine. Now that rod and spring may be just fine - but there is a nut at one end - adjust that nut in or out - that rod is threaded. You may need just a bit of an adjustment to get it to push that button in all the way. - due to the places on the deck it mounts to and so on getting a bit out of wack or just wear and tear over time. This is the answer to the problem - bar none. Personally - I got sick of hitting bumps or going on hills and the mower dying so I bypassed every stupid switch. Lots of tutorials on youtube and online. And Bob’s Your Auntie. If the mower runs just perfect until you go to engage the blade - this is the issue. WARNING - IF YOUR MOWER DIES WHEN YOU GO TO ENGAGE THE DECK./BLADES - YOUR ENGINE STOPS GIVING SPARK - SO YOU WILL HAVE A HEAD FULL OF GASOLINE ON TOP OF THE PISTON (S) - BEFORE ATTEMPTING TO START - REMOVE THE SPARK PLUG (S) AND HAND CRANK THE ENGINE A FEW TIMES - IT WILL SPIT THE GASOLINE OUT OF THE SPARK PLUG HOLES. - REPLACE SPARK PLUGS AND YOU’RE SET AFTER YOU MAKE THE ADJUSTMENTS NEEDED OR REPLACE THAT BAR./SPRING DEAL. IF YOU DO NOT DO THIS - YOU WILL BE STARTING YOUR MOWER - AND YOU WILL BLOW THE ENGINE - MOST LIKELY IT WILL BREAK THE PISTON ARM (S) AND POSSIBLY THE CAM (S) - DO NOT BE THAT GUY!
