Starting issues...got a weird one

Hi all,

I'm helping my friends get their Cub Cadet 1330 going. It was running when they bought it two weeks ago, but when they tried their first mow last week, it ran for 10 minutes, made a popping sound (it sounds like they mean backfired), and then wouldn't start. I went over, found badly deteriorated fuel lines and some minor rubber debris in the bowl. Well, when I say minor, I mean it was quite a few particles, but small in size, still easy to see, though. Anyway, I pulled the carb bowl, cleaned it out, checked the float, it's solid, checked and replaced the needle (I had one from a rebuild kit for the Walbro that wasn't used), and sprayed out the passages I could get to with the carb intact. Checked the spark plug - it's older, but in good shape, so cleaned and put back in. Oil was recently changed - still very clear.

I put it back together, charged the battery and after a few seconds she started and ran like she should. I ran it for a good half hour, mowed some, stopped, waited a minute or two, and started again. Did this three times, all was well. I packed up my tools (about 10 minutes or so), and thought I'd try one more time - now it takes a minute or two before it sounds like it wants to start, though it has strong turn-over. Once it starts, it runs great.

Update since yesterday: When it sat overnight, it started with almost no problem. Ran it for 10-15 minutes, let it sit for maybe 5-10, and hard starting again.
What am I looking at here? Should I break the carb down, remove all the foam and gaskets, and give it a good soak in Berryman's? It seems like it HAS to be a carb issue, but I'm no pro, so I'm asking you guys who are!

It's a Cub Cadet 1330, 12.5 hp Kohler. The mower is in absolutely grade A condition otherwise - no paint scrapes or chips, no rust, only the most minor deck rust, all original paint as far as I can tell. The only things wrong besides the starting issue is a missing headlight lens and the blades need a sharpening.

Any help?

Thanks,
Jack

Cross posting is never a good idea, it just gets confusing.
most of the regular posters use the "Todays Post" drop down from the menu inder the name banner.

Tha nice big bang was unburned fuel burning in the muffler.
This can be either fuel or electrical or both.
Get a spark tester and check for a spark when the engine is cranking & not starting.
Can be something as simple & random as a broken wire just inside a plug.

bertsmobile1 said:

Cross posting is never a good idea, it just gets confusing.
most of the regular posters use the "Todays Post" drop down from the menu inder the name banner.

Tha nice big bang was unburned fuel burning in the muffler.
This can be either fuel or electrical or both.
Get a spark tester and check for a spark when the engine is cranking & not starting.
Can be something as simple & random as a broken wire just inside a plug.

Click to expand...

Thanks, both for the troubleshooting advice and the posting advice. I had initially ruled out bad spark because it did start, usually...but I'll pick up a spark tester and test it when it fails to start. That's the trouble with intermittent problems, though...trying to recreate them so you can test for failures!

Jack

jsmith24 said:

Thanks, both for the troubleshooting advice and the posting advice. I had initially ruled out bad spark because it did start, usually...but I'll pick up a spark tester and test it when it fails to start. That's the trouble with intermittent problems, though...trying to recreate them so you can test for failures!

Jack

Click to expand...

Small problem for you, massive problem for a repair shop where time spent trying to diagnose a problem is not billed.
Scheduled fees allow 15 minutes of billable time for cleaning & diagnosis on most repairs.
The neon tube type plug testers can be left attached while you are mowing so you can just look at it when the mower starts to play up while mowing so you are using your time productively.

bertsmobile1 said:

Small problem for you, massive problem for a repair shop where time spent trying to diagnose a problem is not billed.
Scheduled fees allow 15 minutes of billable time for cleaning & diagnosis on most repairs.
The neon tube type plug testers can be left attached while you are mowing so you can just look at it when the mower starts to play up while mowing so you are using your time productively.

Click to expand...

I hear ya. It was the same for me back when I had to diagnose and troubleshoot things (not mowers...something a tad more complex), and sometimes you could pinpoint the issue in few minutes, other times it would take hours of fiddling and waiting for the gremlin to come back, just so I could charge for the initial book-time. Ugh.

BUT, it didn't occur to me to leave the spark tester in place....as simple as it seems to you, it seems like genius right now to me.

jsmith24 said:

I hear ya. It was the same for me back when I had to diagnose and troubleshoot things (not mowers...something a tad more complex), and sometimes you could pinpoint the issue in few minutes, other times it would take hours of fiddling and waiting for the gremlin to come back, just so I could charge for the initial book-time. Ugh.

BUT, it didn't occur to me to leave the spark tester in place....as simple as it seems to you, it seems like genius right now to me.

Click to expand...

I buy them by the box load ( 24) because I am always loosing them & breaking them.
it is not uncommon to have a mower come in for a biannual service still with my spark tester hanging off the plug from it's last service.
One woud have thought that in 100 or so hours they would have fallen off, but they seem to hang on.

I do the "mow till it fails bit" a lot if I think the mower is safe to use as I have around 5 acres of street verge to maintain as part of the rent and also get called on to do some paddock mowing in peak grass season so I get to do two things at once. Apart from that being under load tends to bring problems out that never surface with the mower running outside the shop door.

bertsmobile1 said:

I buy them by the box load ( 24) because I am always loosing them & breaking them.
it is not uncommon to have a mower come in for a biannual service still with my spark tester hanging off the plug from it's last service.
One woud have thought that in 100 or so hours they would have fallen off, but they seem to hang on.

I do the "mow till it fails bit" a lot if I think the mower is safe to use as I have around 5 acres of street verge to maintain as part of the rent and also get called on to do some paddock mowing in peak grass season so I get to do two things at once. Apart from that being under load tends to bring problems out that never surface with the mower running outside the shop door.

Click to expand...

I had to laugh when I read that bit about buying them by the box...thanks man.

Well some tools are like shop rags, essential but expendable.
I sell a lot to customers who see me using it and ask "where do you get one of those ".
The business is essentially mobile so I an always diagnosing at the customers property so you don't have your tool tray to put tools you have taken from the tool chest in while you are using them.
The mower is on the ground, oft just sitting on the lawn where it stopped so you are working all around it .
And then there are curious kids, who never get told to go away unless there is a clear danger as hungry minds need to be fed.
So it is not hard to forget where you put it down or forget to remove it when finished.