Why does my engine die when the blade is engaged?
I have an older Murray riding lawn mower. Whenever I engage the mower, the engine dies. Otherwise, it runs great.
Please tell us more to help narrow down what the problem is.
1) It is not receiving enough gas or the motor isn't warmed up enough.
2) You are not pushing in on the clutch when engaging the blades/lowering the deck or not pushing in on the clutch far enough.
3) You are engaging the blades/lowering the deck some place that provides too much resistance to the blades turning - such as grass that needs cut.
4) There is something binding in the blade/deck belt path.
5) You are attempting to engage the blades/ lowering the deck while it is in reverse.
I ruled out the clutch safety switch since you are getting it started. I ruled out the safety switch that won't let the tractor run if the blades are engaged on grade with to much of a slope (since you said older). It should be one of the above or some combination of them. With the information you have given I can't narrow it down more than that.
Just posting this in case someone has the same issue.
My mower would run fine without the blades engaged, but when I tried to cut grass i would lose power. I changed the plugs, oil & filter, fuel filter, blades and all that.
Come to find out, I checked one plug and it was dry and the other was wet with fuel. Started the mower and removed plug wire from where the wet plug was and there was no change....reconnected and then removed the other plug wire and the engine died.
So I removed the engine cover. (4) screws on top and (8) screws holding on the cover and the fuel line. I removed the ignition modules (2 bolts) that has the plug wire to the plug not firing. Sears had a new one for 75.00 + tax and shipping, or you can get a new one on amazon for 45.00 with free shipping. Runs perfect now!
I don't know if there is a way to test it to see if it is defective, but I think it was the obvious problem in my case.
Shut off switch, dead mans switch, under the seat. It is not supposed to engage unless it detects weight on the seat. It comes undone or loose.
It sounds like you have a loss of power when you put the extra load on the engine. A possible answer could be as simple as changing or cleaning the air filter. A dirty air filter will allow the engine to run but too rich. The clogged filter acts like another choke. But when the load is applied to the engine, it is too rich and so it dies. Make sure that you are running the engine at full throttle when you do engage the blades.
I've encountered two different problems that might be relevant with a Yardman HE 5135 Ride-on Tractor. First problem was electrical - I forget the details, but basically I had a short (worn wire touching earth) in the cutter deck wire feed that switches in when the deck is engaged. This dropped the voltage to the ignition down to zero (i.e. engine stopped). I had to disconnect faulty wire and bypass it.
Second problem was the very simple one of debris in the fuel tank getting stuck in the fuel line filter and starving the engine of fuel - the engine cut out when the extra load of the cutter deck was brought in. Solution: clean the fuel filter and remove any other debris upstream of it!
I have an Alko powerline ride on mower. Brigs & stratton engine.
I was in the middle of cutting my lawn and after emptying the grass box I tried engaging the blades to start again but the engine started cutting out and back firing. Even if I let the clutch out fully it would start to die.
Reading about this on sites like this I checked all the fuses and the safety switches on the Grass box - seat & break and they all seamed to have continuity. I rang an old guy near me that can fix anything and he told me it was the grass box safety switch.
I told him I checked them and they seamed fine but he just said " they can be temperamental"
Giving the fact he knows what he's talking about I changed it and it worked. So if you think the switches are ok, they might not be. My mower is working perfectly again. Replace safety switches first.
Check butterfly valve in carb.
Same issue. Idled ok. Died down when cutting deck engaged. Valve in carb had failed and wedged almost closed. Starving engine. Enough to run - not to cut properly.
We had the same problem on a new Murray riding lawnmower (B&S engine) and we replaced just about everything we could think of i.e. fuel filter, etc. It turned out to be the carburetor fuel solenoid valve was sticking, so we replaced it. We believe the plunger was sticking causing it to malfunction, therefore the engine would cut out when the blades were engaged for a few minutes. The mechanic temporarily screwed a bolt in, until we received the new part. So far, so good. I'll update if this was not the problem.
Always check your blade spindles and grease them every so many hours per manual. Pto clutches are a good place to go next. Electric things fail. I bought a husqvarna z4824 that had been sitting outside non running for about 3 years in rain and whatever the good Lord threw at it. Needless to say I started tearing down everything cleaning all contacts and changing solenoids and cleaned carb but wound up changing it. Have changed fuel lines all way to carb. Vacuum tube for fuel pump was corroded changed it. Spark plugs, wires, filters. Changed pto switch and ignition switch. Oh and new battery. Needless to say after hundred of dollars and hours of sweat and alot of words later still dies out when engaging blades unless I let it warm all the way up then engage blades at half throttle by shimmying the pto switch off and on a few times real quick until it runs. Also wont start without ether. I have also reset valve clearances with feeler gauge twice. Bout to cut my losses cause I have to cut my lawn.
Turned out to be a bad coil pack in my situation. My mower would do it hot or cold, just started it 1 day out of blue. Start & run fine, all power it world. Then engage blades (engine revved or not) & engine would start bogging down. Turn blades off, revs back up by self. All spindles loose & well greased w/moly grease as usual. Went through uel system, plugs & finally found w/infrared temp gauge R bank shutting down. Changed coil pack, all good. Changed other after that just to make sure good. Runs fine now. 12 yr old Simplicity Cobalt 61” ZTR w/non ICD deck & 27 hp Kohler Non/FI. Mows 6 acres a wk. Have a good day.