Help with Z122E ZTR - PTO Cut Out / Won't Start

[stevenlmas]

Really scratching my head here with my Z122.

Symptoms:

• All season: generally will not start without battery booster attached
• Yesterday, I started w/ booster, Mowed for ~15 minutes, then PTO shut off & blades stop
• Restarted w/ Booster, but PTO won't engage

Attempted:

• Replaced battery
• Replaced PTO switch w/ $20 Amazon PTO - worked fine for about a day, then back to not starting without booster
• Replaced PTO switch w/ $140 Kubota PTO switch - started with booster, mowed for about 5 minutes, PTO cut out.
• Cleaned contacts from PTO to main harness
• Removed all fuses, cleaned contacts, and replaced with new fuses
• Seat switch seems OK - shuts off when I stand up

 

[5030]

First thing I'd do is install a metal paper clip in the OPC (seat switch). While I own a few Kubota's not familiar with that moedl, Is it a gas V-twin or a diesel? If it's a gasser, Kohler or Briggs or whatever and the battery goes dead, either the under flywheel alternator is an issue or the external voltage regulator (on the side of the engine attached to the shroud or you have lost one or more of the magnets that are epoxied to the flywheel. The flywheels come off easily by loosening the top nut and smacking the threaded end with a brass hammer (so as not to damage the threads) If it's a diesel, the external alternator needs replaced. Kubota alternators are all internally voltage regulated or the drive belt is too loose... I'd check all the battery to motor connections first and clean and brighten them.

 

[stevenlmas]

Thanks @5030 ! This is a gas V-twin.

Yesterday, I put the battery booster on the battery, started it, and left it there instead of removing. I was able to mow my lawn and disengage / re-engage the PTO at will. I was thinking it might be solenoid, but I'll check the flywheel and regulators before I spend more money on a solenoid

 

[thclimer]

Some tractor owners have reported corrosion inside the battery terminal cables which is very difficult to detect. Using a jumper cable in place of the battery cable is one way to determine if your cables are less than adequate to transmit the power required for starting.

 

[Richard001]

All indications are that the alternator is not charging the battery. You have thrown a lot of parts at it, and it still doesn't work.

If you don't have a voltmeter, get on. Check the battery voltage before you try to start the engine. A fully charged battery should show 12.6 V DC See more information below:

A battery’s condition can be monitored by checking the electrolyte’s specific gravity with an inexpensive D-I-Y battery hydrometer to determine the percentage of sulphuric acid it contains.

A fully charged cell at 80 degrees F would show a specific gravity of 1.265. If all six cells are fully charged, an accurate digital voltmeter reading of battery voltage would show 12.68 volts.

Specific gravity for a 50 percent discharged cell would drop to 1.19 and battery voltage would fall to 12.24.

When specific gravity reaches 1.12, the cell is fully discharged and battery voltage falls to 11.89 volts, assuming the specific gravity is the same in all six cells.

Because specific gravity is affected by temperature, subtract .004 per 10 degree drop below 80 degrees F.

After you get the engine running, (PTO OFF), run the engine at about half throttle. Measure the voltage at the battery terminals. You should see about 14.5 VDC. If not, your alternator or the regulator is not working.

If you see the 14.5 volts, but if it drops below 12V when you engage the PTO, your have a charging problem.

Richard

 

[stevenlmas]

Thanks Richard - I'm not a complete dolt with small engines, but electrical components have always eluded me. This sounds simple enough - I'll give it a shot this weekend.