Random Hard Starting

jp2code

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Equipment
L4400
Jun 9, 2017
40
0
6
LONGVIEW, TX
www.jp2code.net
I have a Kubota L4400DT.

The engine turns over fine and the battery is nice and strong. Sometimes the engine starts immediately, but other times I can crank and crank and it will not start at all.

A couple of possible clues:

  • When it doesn't crank, after a long {burr-rur-rur-rur-rur} of the engine, sometimes I let off the key and it sounds kind of like the engine turns backwards just a bit. Maybe it's just the compression letting off and turning the engine back a quarter turn or so.

  • As I turn the key, sometimes I hear a single relay click but other times I hear several clicks. The sound is like one or more relays is energizing and then loses contact. I think my non-starts occur typically when I hear several relay clicks. Like I said, it is intermittent.

How would I go about troubleshooting this?

Note: Last fall, my L4400 would not crank every time, and it left me stranded miles from home on one occasion. I suspected the "under-seat safety switch" and the "neutral gear position safety switch". I was able to remove the "neutral gear position" switch and test it, but the Delphi connector on the "seat safety switch" was crushed and I could not get it apart without destroying it. I sent it to the Kubota dealership to get it fixed, and the bill came to $1475. They said it took lots of man-hours to diagnose the problem because it was intermittent, it turned out to be the "seat switch". I'd rather not send my tractor back to the Kubota dealership until after I have won the lottery.
 

SidecarFlip

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M9000HDCC3, M9000HD, Kubota GS850 Sidekick
Oct 28, 2018
7,197
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USA
Probably the fuel cut solenoid if it has one. They can and will cause cranking but no start
 
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whitetiger

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Kubota tech..BX2370, RCK60, B7100HST, RTV900 w plow, Ford 1100 FWA
Nov 20, 2011
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Your tractor has 2 PTO safety switches, one for the Crank circuit and one for the Operator Present circuit which controls the fuel shutoff solenoid. Hold back on the PTO lever and crank it, see if it starts up.
 
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jp2code

Member

Equipment
L4400
Jun 9, 2017
40
0
6
LONGVIEW, TX
www.jp2code.net
Dave,
How did you find that "fuel cutoff solenoid" on Messick's? I've tried drilling down into the L4400 section and a direct search for the text, but it isn't coming up.

Your tractor has 2 PTO safety switches, one for the Crank circuit and one for the Operator Present circuit which controls the fuel shutoff solenoid. Hold back on the PTO lever and crank it, see if it starts up.
I wished I knew how to just bypass all those safety features. They only provide problems as the tractor gets old.
 

jp2code

Member

Equipment
L4400
Jun 9, 2017
40
0
6
LONGVIEW, TX
www.jp2code.net
It took a long time for the $200 fuel shutoff solenoid to get here, but I got it replaced.

Apparently, it was not the problem. The tractor is still difficult to crank.
 

Mark_BX25D

Well-known member

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Bx25D
Jul 19, 2020
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Troubleshooting beats parts swapping. It's almost always faster and cheaper. Less frustrating, too.

Those safety switches are there for a reason, and they are not difficult to replace. Probably best to start there.
 

SidecarFlip

Banned

Equipment
M9000HDCC3, M9000HD, Kubota GS850 Sidekick
Oct 28, 2018
7,197
546
83
USA
Wowzer, 200 bucks. I feel honored. The OEM one for my M9000's are 100 bucks from the dealer,and 35 on Flea-Bay. Got one of each and no difference between them.
 

jp2code

Member

Equipment
L4400
Jun 9, 2017
40
0
6
LONGVIEW, TX
www.jp2code.net
Troubleshooting beats parts swapping. It's almost always faster and cheaper. Less frustrating, too.

Those safety switches are there for a reason, and they are not difficult to replace. Probably best to start there.
I'm happy to troubleshoot more, but tell me where.

The seat switch has been replaced. The gear switch ohms out as good.

What else is there? I don't have a wiring diagram, so I don't know what all could be the problem.
 

armylifer

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Lifetime Member

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BX1860, FEL, RCK54P MMM, BB1548 Box Scraper, Quick Hitch, Piranha Bar, BX6315
Mar 26, 2013
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Thurston County, WA
Because your original post said that the problem is intermittent, I suggest the following. Check to see if all the fuel lines are tight. Start at the engine and work all the way back to the fuel tank, if necessary. It is possible that air is getting into the fuel line and this will cause a no start condition. Make sure that you also check the fuel injector lines, one of them may have vibrated loose, that would also cause the condition you described.

There is one more possibility, one or more of the glow plugs may not be working. Check to see if there is white smoke coming from the exhaust while cranking the engine. It there is, that is a symptom of bad glow plugs. Hope this helps.
 

armylifer

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BX1860, FEL, RCK54P MMM, BB1548 Box Scraper, Quick Hitch, Piranha Bar, BX6315
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Great for you. I am happy that it turned out to be something cheap to fix. Thank you for letting us know that you found the issue.
 
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Russell King

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L185F, Modern Ag Competitor 4’ shredder, Rhino tiller, rear dirt scoop
Jun 17, 2012
4,606
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Austin, Texas
And if the problem returns then buy a OEM switch, they are probably higher quality
 

PoTreeBoy

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L35 Ford 3930
Mar 24, 2020
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WestTn/NoMs
Glad you got it going. If you're going to be doing your own maintenance, I highly recommend the WSM (WorkShop Manual). I don't see a free one on www.kubotabooks.com, but you can get one from a dealer or Messick's for about $100. Make sure you get the one for your specific model.