Troubleshooting a 125 - Cutting out and dying - No load

[GaryC]

Hello,

Today, before any serious use, our (new to us) 125 started to lose power and die after idling for a while.
(Engine ran fine yesterday)

I was able to get it started again three times (but only with choke until firing - even though engine was warm) and from high RPM it would run for a minute and then fall off and die.
The last time the RPM was surging (briefly falling off) before again falling off and dying.

I have not had a chance to check the strength of the spark as it was sitting out in the open and it had started to come down.

Having not worked on troubleshooting ignition problems for about thirty years, I thought I'd again reach out to the pros.

My hunch is that the spark is weak and maybe the coil is going ?
Spark lead ?

The spark plug lead looks really tired and the coil does not look to be from this millennium. Not at all impressed with the way the lead connects with the plug and played with it a bit. It's all on the list.
- But the previous owner said he'd recently changed the plug, and did points and condenser regularly (it had new points 15 hrs ago now).

The plug is quite black today . . .

The only other thing to mention is that yesterday, again, the choke cable had frozen so I gave it some WD40 at both ends. Any chance some might have crept into the carb through the choke shaft to cause a problem?

Otherwise, the engine, when running, sounds great !

Thanks,
GaryC
- who has been known to shovel really long driveways, like today.

[athomas]

Maybe not getting fuel ?

[john hall]

Originally Posted by athomas

Maybe not getting fuel ?

Yep, sounds like its starving for fuel, burning whats in the carb bowl out and then having to wait for it to fill up again. Time to take the line off and see if there is good flow to the carb.

[Merk]

Your IH Cub Cadet needs 3 things to run. air-fuel and a spark.

Air:
Try running your Cub Cadet with the air filter off. I had a Briggs engine that the filter look ok. Looks can be deceiving. I had air filters freeze up while blowing snow.

Fuel:
Fuel in gas tank?
Fuel less than 30 days old?
Is your fuel shut off open?
When is the last time the fuel filter been change(providing it has one)?

Spark:
How old is the spark plug?
What brand spark plug?
How does the plug wire terminals look?
Is the spark plug wire on correctly?
What condition/age is the battery in?

This is a list of things I would check.

[sawdustdad]

If pulling the choke keeps it running, even if only momentarily, it's a clear indication that it's a fuel supply issue.

Check for good flow of fuel from tank to carb. Remove and rebuild carb. If it starts and runs well for a few minutes, then I'd say it's less the carb than the fuel supply to it.

[GaryC]

Thanks guys.

The fuel is about 90 days old. Shut off is open, tank is two thirds full.

I don't like the looks and feel of the spark plug wire at the plug (didn't look at the coil end today)

I'm guessing the filter is less than fifty hours (the previous owner did basic maintenance). I'll have a look at it tomorrow.
- But it has been a bit wet here and I can see how it could have iced two days ago - as the choke cable did.

PLUG :

I think I remember him saying the plug was fairly new. Not sure the brand.
What brand do I not want . . . ?

BATTERY :

I think the battery is "OK" but it is not that strong. I don't know it's age. Often have to jump it at first.

* I had been noticing that the meter would not raise that much with higher RPMs so a couple days ago I tightened the Gen/Starter belt - but there wasn't a noticeable change at the meter. HOWEVER today, one of the last times I got it running I noticed that the meter was showing really high charging.

- what is that about? Battery ? Generator acting up ?

Re : Age of the fuel, I would have thought that old fuel would cause the engine to cough / sputter, rather than cause a sudden full shut down.

Also, I don't understand how a blockage in the fuel line (check the line) would all of a sudden cause the engine to die right after it was running well.

- the fuel lines are brand new, by the way.
- I don't know how old the filter is but it doesn't look old.

John, when you're suggesting the engine is waiting for the carb bowl to fill up again . . . is that in relation to the single incidence of "surging" I mentioned, or the fact that it's all of a sudden falling off and dying (four times now).

Thanks,
Gary

[GaryC]

Battery :

Often have to jump it after not getting it started in the first minute and wearing it down. But even before first cranking it's not very impressive.

[GaryC]

Hey sawdustdad,

Thanks for the tip.

I never tried pulling the choke as it was dying this afternoon.

Yes, as mentioned, today it would start and run fine for a few minutes and then die quickly - within five seconds. And it's been running fine this winter.
So it seems to point to supply rather than the carb. (air or fuel)

And, doesn't a carb's performance decline slowly (unless of course it gets gummed up)?

[Billy-O]

Did you say filter? Or did you mean sediment bowl?

If you have inline filter, chances are that it is clogged up already and slowing down fuel delivery.....even if it isn't that old. You're better off with sediment bowl.

[Merk]

Originally Posted by GaryC

Thanks guys.

The fuel is about 90 days old. Shut off is open, tank is two thirds full. I would replace the fuel with fresh fuel.
I

Gas has a shelf life of 30 days. Best thing you can do for all your small engines is keep fresh fuel (less than 30 days old) with a stabilizer in it. Todays gas doesn't act the same as yesterdays gas.

PLUG :
I think I remember him saying the plug was fairly new. Not sure the brand.
What brand do I not want . . . ?

I use Autolite 216 spark plugs. Champion plugs foul out too easy.

BATTERY :

I think the battery is "OK" but it is not that strong. I don't know it's age. Often have to jump it at first.

* I had been noticing that the meter would not raise that much with higher RPMs so a couple days ago I tightened the Gen/Starter belt - but there wasn't a noticeable change at the meter. HOWEVER today, one of the last times I got it running I noticed that the meter was showing really high charging.

Check the wires for poor connections. A good place to start is your ground wire. Something is not right if you have to jump your Cub Cadet often. Your Cub Cadet needs a good battery-electrical system to run. I would have the starter-generator check to make sure it is running right. I would replace the battery or keep a battery tender on it.

I'm guessing the filter is less than fifty hours (the previous owner did basic maintenance). I'll have a look at it tomorrow.
- But it has been a bit wet here and I can see how it could have iced two days ago - as the choke cable did.

Either replace the air filter or take the filter some where it is warm. I have used brake clean on the throttle and choke cables to help dry them out.