Turning but not starting - basic mechanics?!
Turning but not starting - basic mechanics?!
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Discussion

Hawk51

Original Poster:

11 posts

65 months

Friday 28th May 2021
quotequote all
Hi, Please be patient, I’m learning from the ground up (grass up, in my case)!

I have been unkind to a new-to-me (but not actually new) petrol ride-on mower (John Deere x125). I worked it on a patch of long grass which must’ve been damp underneath as it struggled, cut out once, so I moved to shorter grass. Happy for a further 20m, then it cut out. Turns over, but doesn’t fire up. Oil was in range before mowing started, though low end (didn’t mow for long so shouldn’t have thought it’d be this). Petrol when it cut out was ‘1/4 tank’ but these gauges are notoriously unreliable on this mower, so running out is a possibility. Didn’t start up again when more added. My list of possible problems was something like this:
- Overheated - maybe, but didn’t start when cooled
- Overworked - yes, almost certainly (never mow in a hurry…)
- Ran out of fuel - air now in fuel system, or dirt in carburettor?
- Blocked air filter (looks ok but what do I know?!)
- Something Else Terrible
Is there anything I can do as a novice to check anything and get a diagnosis, or even fix? What would you do? Or is it just a ‘call the mechanic’ job?
Thank you

paintman

7,860 posts

220 months

Friday 28th May 2021
quotequote all
You need:
A spark at the right time.
Fuel in the right quantity and if an injected engine at the right pressure & at the right time.
Compression
Air.

Did it just cut out or did it seize & then free off as it cooled?

Hawk51

Original Poster:

11 posts

65 months

Friday 28th May 2021
quotequote all
It just cut out and wouldn’t fire up again. I didn’t keep trying, just let it cool. Exactly the same when it was cool. Air filter looks fine. I’m guessing the fuel was the problem, and that 1/4 tank on the gauge is low enough for air or dirt to get in the system? It’s mowing some pretty bumpy areas so could be that was enough for the small amount of petrol to not be enough to prevent air getting into the system? Clutching at straws…!

Thats What She Said

1,180 posts

118 months

Friday 28th May 2021
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Have you checked to see if the blades are clogged up with long wet grass?

rustednut

807 posts

77 months

Friday 28th May 2021
quotequote all
Petrol? Single cylinder?

Be worth re newing the spark plug(s), and checking its connection before doing anything else.

Hawk51

Original Poster:

11 posts

65 months

Friday 28th May 2021
quotequote all
Thats What She Said said:
Have you checked to see if the blades are clogged up with long wet grass?
I want to, but don’t have an easy/safe way to lift it enough to do it properly. But surely this shouldn’t stop it firing up, because the blades only engage when you flip the lever? Unless it’s safety thing. My neighbour has a jack for his so I’m going to ask if I can borrow it

Hawk51

Original Poster:

11 posts

65 months

Friday 28th May 2021
quotequote all
rustednut said:
Petrol? Single cylinder?

Be worth re newing the spark plug(s), and checking its connection before doing anything else.
Yes petrol, single cylinder. Sort of assumed it wasn’t spark plugs because it sounds like it’s doing the first part of starting, but the engine cuts out immediately if that makes sense. Turning over and sounds like it’s firing up then dies before it does

rustednut

807 posts

77 months

Friday 28th May 2021
quotequote all
Hawk51 said:
Yes petrol, single cylinder. Sort of assumed it wasn’t spark plugs because it sounds like it’s doing the first part of starting, but the engine cuts out immediately if that makes sense. Turning over and sounds like it’s firing up then dies before it does
Assuming it was running ok and died gently, not violently (engine damage), then it sounds like fuel or ignition (unless timing has slipped). You say you have put fresh petrol in, so it's worth the plug change. Will also give a clue as to how engine has been running when you look at the old plug.

No point getting stuck in further until you cover the basics.

Hawk51

Original Poster:

11 posts

65 months

Friday 28th May 2021
quotequote all
rustednut said:
Assuming it was running ok and died gently, not violently (engine damage), then it sounds like fuel or ignition (unless timing has slipped). You say you have put fresh petrol in, so it's worth the plug change. Will also give a clue as to how engine has been running when you look at the old plug.

No point getting stuck in further until you cover the basics.
Great, sounds like a plan. Yes it died gently.

tapkaJohnD

2,000 posts

234 months

Saturday 29th May 2021
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Do you have the Operator's Manual that originally came with it?
https://images.homedepot-static.com/catalog/pdfIma...

And this specialist, John Deere page has an "Engine won't start" problem age: http://tractorgearbox.com/jd_x125_problems.html

Good luck!

markcoznottz

7,155 posts

254 months

Tuesday 1st June 2021
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He’s just going through a rough patch.

eltax91

10,769 posts

236 months

Tuesday 1st June 2021
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Be sure you don’t have a problem with a safety switch somewhere. I tore the entire fuel system apart on my Westwood only to discover that a faulty brake pedal switch (must have brake pressed to start) was cutting spark.

The other thing that’s possible is degrading fuel lines. Modern ethanol based fuels degrade the inside of the fuel lines, to the outside you would have a clue anything was wrong, but in my case the fuel isolating tap was rammed full of bits of rubber fuel line and the fuel was barely trickling through. The longer I left it, the longer it would run for, which turned out to be the carb bowl filling with varying level of fuel!

rev-erend

21,623 posts

314 months

Tuesday 1st June 2021
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markcoznottz said:
He’s just going through a rough patch.
Give him a break, he just wants to cut through the long grass to the problem.