Scag Freedom Z engine won't start after regulator replacement

Farmer10021

Forum Newbie
Joined
Aug 7, 2021
Threads
1
Messages
3
  • / Scag Freedom Z engine won't start after regulator replacement
Hi
I have a Scag Freedom Z mower, (It has a KT725 engine) it had battery charging issues which turned out to be the regulator.

I also had to clean and lubricate the starter cause it had locked up.
However after the engine was assembled and running with the new regulator the engine didn't have much power and would bog down to the point of stalling when mowing.
Eventually the engine backfired and cut out, and I haven't been able to get it to start since. I have tried adjusting the gap on the ignition coils incase that was wrong, replacing the fuel pump, and replacing the carburetor, but it still won't start, and will sometimes backfire loudly when I crank it.

It has spark, it gets fuel, and there's plenty of compression.

Any advice would be appreciated!
 

Scrubcadet10

Moderator
Staff member
Joined
Sep 24, 2017
Threads
248
Messages
6,431
  • / Scag Freedom Z engine won't start after regulator replacement
If you have a good spark, and the combustion chamber is getting fuel and you have compression.. to ME that leaves one thing.. Spark at the correct time...i would look at the flywheel key.
have you removed the flywheel recently?
 

Farmer10021

Forum Newbie
Joined
Aug 7, 2021
Threads
1
Messages
3
  • / Scag Freedom Z engine won't start after regulator replacement
If you have a good spark, and the combustion chamber is getting fuel and you have compression.. to ME that leaves one thing.. Spark at the correct time...i would look at the flywheel key.
have you removed the flywheel recently?
Flywheel had to be taken off to replace the regulator, so yes.
 

Scrubcadet10

Moderator
Staff member
Joined
Sep 24, 2017
Threads
248
Messages
6,431
  • / Scag Freedom Z engine won't start after regulator replacement
Did you torque the flywheel back to specification?
if not the flywheel can shift on the tapered shaft and shear the key.
 

Farmer10021

Forum Newbie
Joined
Aug 7, 2021
Threads
1
Messages
3
  • / Scag Freedom Z engine won't start after regulator replacement
Did you torque the flywheel back to specification?
if not the flywheel can shift on the tapered shaft and shear the key.
Wow, you were spot on!
The flywheel key had sheared.
I had assumed my impact wrench had torqued it enough, but I guess not.
 

bertsmobile1

Lawn Royalty
Joined
Nov 29, 2014
Threads
64
Messages
24,647
  • / Scag Freedom Z engine won't start after regulator replacement
You are not alone.
BAd news is now there will be a little damage to the edge of the key slots on both the flywheel & the crankshaft that will need a little attention.
The tinest of burrs will prevent the tapers locking and you will be shearing keys from here to eternity
 
Top