Exmark LazerZ HP with stalling issues

[Mower Maniac]

LazerZ HP engine stalls only when blades are engaged & making either a right or left turn. If you pull the drive levers back to neutral immediately after the turn the engine revs back up & you can proceed to go forward with blades engaged & @ full speed with no apparent problems.
I've completely disassembled & cleaned the carb, inspected the air filter, replaced the seat safety switch, the parking switch & the PTO Clutch harness. Tested the PTO clutch "cold" (prior to starting the engine) @ 2.0 Ohms & "hot" (after running the mower for 15 minutes) @ 2.6 Ohms. I replaced the PTO clutch last year with a new one due to the old one failing the Ohms test. This machine problem is driving me crazy! I'm a new member. Has anyone had this symptom with their Exmark?

 

[Rivets]

First thing I would be checking is, are both cylinders operating properly. Sounds like you may be loosing one cylinder. We also need all engine and unit numbers.

 

[Mower Maniac]

First thing I would be checking is, are both cylinders operating properly. Sounds like you may be loosing one cylinder. We also need all engine and unit numbers.

Thanks for your advice. Sorry for the long pause! Got busy running my A/C business & forgot to check back.
M/N: LHP23KC523 S/N: 777725. MOTOR: Predator 708cc. Motor Item #62879.
I purchased this mower about 2 years ago from a local / well established lawnmower shop (we mow our property approximately 3 acres every 7 - 10 days during the growing season - approximately 7 - 8 months in MS). He previously had performed repairs on my older ExMark & I purchased it after my older ExMark had an engine failure.
The owner let me test it on his property before I made the purchase. The motor looked new, ran & mowed perfectly and he said he had put 4 - 6 hrs of run time on it cutting his own grass. My reason for not taking it to a shop is because it normally takes a few days or so to get it back, the grass needs to be cut & I figured there couldn't be much wrong with it since it runs except when turning around.
My logical reasoning needs to ask: How could the mower cut 6" tall / thick grass @ maximum forward speed if I've lost 1 cylinder? BTW: I forgot to mention in my previous post that I also replaced both spark plugs when I cleaned the carb, etc.

Just need to know what to check next. I don't have a compression tester to test the cylinder. I've previously check spark @ both plugs & there was fire in the hole - so to speak.
Thanks for your help!
Mower Maniac

 

[john543]

I'm willing to say it's one of the arm switches loosing contact. I've had the same problem and found that the plug was loose fitting on the switch and with all the grass and dirt it would loose contact and kill the motor.
Switches are NC so if the wire is a loose contact it results in a open state = motor dies.

 

[geelee]

once the parking brake is released the seat switch is the only one that matters. can bypass with a wire jumping the connection, for testing only. if your system has a tilt sensor bypass and leave it that way

 

[john543]

I've tried jumping the seat switch it still did the same thing. Releasing the brake acts the same as if you pull the arms in without releasing the brake motor shuts down. I still say it's the plugs not making a good contact on the switch. I cleaned all my switches found corrosion in three out of four plugs. Before doing this I would have to yank the brake up & down several times then the motor wouldn't stall for a while then while mowing out of the blue it would stall and I would have to do the routine over again. This is what led me to an intermittent wiring issue caused by weak plug ends not making a good contact and vibration of the motor not helping.

 

[StarTech]

once the parking brake is released the seat switch is the only one that matters. can bypass with a wire jumping the connection, for testing only. if your system has a tilt sensor bypass and leave it that way

Hmmm. The IPL is showing a normally closed switch for the seat switch so jumping it won't work.

 

[geelee]

I will go slow so even star will understand, yes the switch is normally closed. on this system when you get off the seat it openssssssssssss the switch. Now 48 years in this field and 25 on exmark I know what Im talking about. I only answer what im sure of unlike some others. If you worked on exmark you should know this too. Star this is the second time you jumped on what I said and were proven wrong.