Zero turn mower only restarts after sitting a couple days

ChrisSl789 · May 8, 2021

I have been having a problem restarting my Husqvarna MZ6128 zero turn mower after running it for a few hours. This has been happening for a couple of years now, so I know how to work around it but would like to address to problem . It is a real puzzle to me, and any thoughts would be welcome. Here is what I know:

1) When I finish mowing, or if I have to stop in the middle, my mower will not restart. When I turn the key, I get nothing. No clicks, no engine turn over. Nothing. I have been testing this for a few years after I finish mowing and it is always the same... nothing.
2) After it sits for a a few days, it will start with no problem. My "solution" is to always mow my entire yard (which takes a couple hours) and park it when done. Without fail, it will be fine the next time I need to mow in a week or two.
3) I don't think it is related to heat. I mowed the lawn on Friday afternoon, and tried to start it on Saturday at noon and got nothing. If I wait until Sunday or maybe Monday, it will start with no problem.
4) When it has been sitting long enough to start, I can start and restart it as many times as I want as long as I don't move it (tested this many times over the last few years). However, if I drive a short distance (e.g. from the barn to the house, 75 yards) it will most likely not start again (I don't test this very much since I can't mow for a few days).

Any ideas on what could be causing this? Or other things I should check? I can't think of anything where letting it sit for one day doesn't "fix" the problem, but sitting 2 or 3 days does allow it to start again.

big bubba · May 8, 2021

replace existing w/large inline fuel filter, be sure you're getting a strong flow from tank when you replace
use only ethanol free fuel w/treatment. change the spark plug(s) as well. ensure the temp rating on the plugs is correct for the engine

quicksandfarmer · May 8, 2021

I originally thought fuel filter but OP wrote

ChrisSl789 said:
No clicks, no engine turn over. Nothing.

That's electric.

When it's in that mood I would get a voltmeter and a helper and trace the path from battery to starter when the key is turned. Something that is supposed to be conducting electricity isn't. You need to find out what and replace it.

Intermittent problems like this tend to get worse.

quicksandfarmer · May 8, 2021

If I had to guess I'd say one of the safety switches. Mowers have switches to keep it from starting unless the blades are disengaged, a foot is on the brake and a butt is in the seat. My guess is a switch is sticky, the spring on it isn't strong enough to pull it closed immediately. But after a few days of sitting the slow pressure eventually closes it.

If my theory is correct I'd think the blade switch is the most likely culprit because the others would be open when the mower is sitting.

LittleBill21 · May 8, 2021

yea its an electrical, nothing to do with fuel, start at the battery and work your way back till you lose voltage.

geblackwell · May 8, 2021

Jiggle the the switch that starts the mower blades turning up and down rapidly. That helps on some

PILOON · May 8, 2021

Another possibility----

Ignition switch inner contacts might not be doing their job.
The lube used might just be caked hard preventing start contact.
A squirt of WD40 (or similar solvent) often cures that problem.

Also, safety switches for free movement to do their job as designed.
(a 'jumper' temporarily installed could eliminate those possibilities)

MoKelly · May 8, 2021

quicksandfarmer said:
If I had to guess I'd say one of the safety switches. Mowers have switches to keep it from starting unless the blades are disengaged, a foot is on the brake and a butt is in the seat. My guess is a switch is sticky, the spring on it isn't strong enough to pull it closed immediately. But after a few days of sitting the slow pressure eventually closes it.

If my theory is correct I'd think the blade switch is the most likely culprit because the others would be open when the mower is sitting.

^^^ This is my guess as well. Check that blade engagement switch.

MoKelly

CoyPatton · May 8, 2021

quicksandfarmer said:
I originally thought fuel filter but OP wrote

That's electric.

When it's in that mood I would get a voltmeter and a helper and trace the path from battery to starter when the key is turned. Something that is supposed to be conducting electricity isn't. You need to find out what and replace it.

Intermittent problems like this tend to get worse.

I doubt his problem is between the battery and the starter.
It is more likely to be a safety switch issue. Since it happens if he moves it with it running for even a short distance, my guess would be a neutral safety switch. To test this and other safety switches, they must be tested while not working.
They are typically straight forward switches like a household on/off light switch where when ‘open’ there is lots of resistance to electrical flow and when closed there is little to no resistance present.
If the mower is starting the problem is not present and will be near impossible to locate.
One other test to try is to see if there is any adjustment to your control arms to better engage the neutral safety switch.