Help!?! Tiger Cub/Kaw FH601V Runs Erratically, Dies on Blade Engage

[indiggio]

Neither Scag or Sears Make there own batteries.
Don't buy batteries from discount chains (son worked at battery plant Wal-Mart buyers 3rd run batteries)but other than that CCA is most important. Higher the better. Most if not all lawn mower batteries have a 90 day warranty. They are not really built very well(son worked at battery plant). Best thing to do is have the battery tested by a auto parts store. most will do it for free.
You said this happened when you changed the battery. I would look at the battery cables for clean and snug. Find where the negative cable connects to frame and remove clean and reinstall.

Thanks for the suggestion. I will check the wires/connections as well.

I can't say for sure the problem is the battery, but just wondering if a bad battery or one that isn't as powerful as an original could cause these types of problems?

 

[BlazNT]

Thanks for the suggestion. I will check the wires/connections as well.

I can't say for sure the problem is the battery, but just wondering if a bad battery or one that isn't as powerful as an original could cause these types of problems?

I can't say for certain that it is the cause either. But I did have a truck one time that I had to replace the battery cable ends so that the alarm system won't quit going off. You just never know with electricity.

 

[indiggio]

I can't say for certain that it is the cause either. But I did have a truck one time that I had to replace the battery cable ends so that the alarm system won't quit going off. You just never know with electricity.

I had another tractor that I checked the battery, tested it and it wouldn't crank the tractor.
I cleaned off the negative terminal and connector, reconnected everything and then it started right up.

 

[Mad Mackie]

I use the 420 CA/ 350 CCA batteries from Tractor Supply. This is an Exide battery, the sealed type. I have these batteries in three machines and haven't had any problems with them, I do replace them at the beginning of the 4th season. I just replace the battery on my 2008 Tiger Cub, this is the 3rd battery. My Hustler is due this spring being a 2012 machine. Batteries do have a date of manufacture on them.
Your Tiger Cub may be older than you think as Scag does a 24 month production run of most models and where the machine serial number falls into the serial number range will tell you about what part of a 24 mouth run it falls into. The engine also has a build date and location in the code numbers.
As for the Kawasaki engine, I have replaced ignition coils on several Kawasaki twins that were 2006 or older.
The coils have internal solid state components that can fail when the engine is hot. When cold, they check out electrically as OK.
Another problem that I have seen on many older machines is accumulation of dirt under the engine flywheel. One machine that I serviced, I had to remove the flywheel and dig out the caked crud that was baked into the area inside the stator. This engine was overheating both the stator and the ignition coils. After cleaning this engine under the flywheel and the cylinder fins, it would run for about two hours and then quit like the key switch was turned off. At that time I replaced the ignition coils and instructed the customer as to how and when to clean the engine with HP air.

 

[indiggio]

I use the 420 CA/ 350 CCA batteries from Tractor Supply. This is an Exide battery, the sealed type. I have these batteries in three machines and haven't had any problems with them, I do replace them at the beginning of the 4th season. I just replace the battery on my 2008 Tiger Cub, this is the 3rd battery. My Hustler is due this spring being a 2012 machine. Batteries do have a date of manufacture on them.
Your Tiger Cub may be older than you think as Scag does a 24 month production run of most models and where the machine serial number falls into the serial number range will tell you about what part of a 24 mouth run it falls into. The engine also has a build date and location in the code numbers.
As for the Kawasaki engine, I have replaced ignition coils on several Kawasaki twins that were 2006 or older.
The coils have internal solid state components that can fail when the engine is hot. When cold, they check out electrically as OK.
Another problem that I have seen on many older machines is accumulation of dirt under the engine flywheel. One machine that I serviced, I had to remove the flywheel and dig out the caked crud that was baked into the area inside the stator. This engine was overheating both the stator and the ignition coils. After cleaning this engine under the flywheel and the cylinder fins, it would run for about two hours and then quit like the key switch was turned off. At that time I replaced the ignition coils and instructed the customer as to how and when to clean the engine with HP air.

Super Mackie! Thanks for all that.
I simply put in a DieHard replacement without doing a lot of research. I'm wondering if it doesn't have enough CCA or reserve power.

Also I now want to check the flywheel and clean anything out of there. Thanks for that info as well!

 

[bertsmobile1]

Mackie, thanks for all that great information! Very much appreciated.
It's a 2005, so I don't know if that's what you mean by an older model or not?

Could all this be due to battery? I replaced the original Scag battery that would no longer crank with a Sears Diehard 2 years ago.
Thinking back, all this seemed to start after I replaced the battery.
Should I get another original Scag battery instead?

Thanks!

Usually not the battery as the ignition is self energising.
Some Kohlers ran an externally powered advance unit but I think they have all ben dropped.
The only thing a bad battery can do that affects the running of the engine is not supplying power to the fuel shut off solenoid.

Another reason to seperate your problem between ignition and fuel.
Once you have done that you can start jumping into the engine as Mac has described.

You need to diagnose the probelm first before you run around fixing problems that you do not have and potentially introducing more problems.

 

[indiggio]

Usually not the battery as the ignition is self energising.
Some Kohlers ran an externally powered advance unit but I think they have all ben dropped.
The only thing a bad battery can do that affects the running of the engine is not supplying power to the fuel shut off solenoid.

Another reason to seperate your problem between ignition and fuel.
Once you have done that you can start jumping into the engine as Mac has described.

You need to diagnose the probelm first before you run around fixing problems that you do not have and potentially introducing more problems.

Ok, thanks.

It has no problems cranking the engine and it starts after a few cranks, so perhaps it's not the battery.
It's also been acting funny on startup, as it fires right up, runs for a few seconds, then dies.
It did this 2 or 3 times before it fired up and stayed running, then it ran ok.

I checked it yesterday and there was over 12 volts on the battery while the mower was off.
At full throttle, there was like 14.29 volts, so I think the charging system is working...

I took the cover off the engine and looked around,, but didn't find anything.
Both cylinders and coils were very clean, no gummed up grass or leaves or anything.
I checked the connection to the coils and they seemed fine.
I also checked the ground wire where it meets the engine block and that is solid.
I also removed the ground wire from the battery and wire brushed both the terminal and connector, both are now shiny clean.

I popped off the blade belt and spun all of the various pulleys and they all spun easily.

I took the mower back out to the shed and engaged the blades and they spun up ok.
I did this 3 or 4 more times and it didn't bog down or stall.
After I shut the blades for the last time, back came the surging engine.
I found that if I play with the choke, I can get it to a point where it's not surging anymore.

I would think if there was dirt in the carb, that it would run like crap all the time and not just sometimes?

Could it be something going on after the engine warms up a bit?

Thanks!

 

[bertsmobile1]

Loose carb mounting bolts can do that.
As stated earlier surging is caused by insufficient fuel being supplied to the cylinder, so the engine slows down which causes the govenor to open the throttle wider to increase the speed.
During the slower running the float bowl fills up and an opening butterfly puts a strong signal on the venturi so it sucks more fuel and accelerates, then runs out of fuel and decelerates and the whole process repeats itself at infinitum.

Surging is fuel related about 99.9% of the time.
The other 0.1 % it is a fualty govenor.
Start the mower and when it is playing up put your finger on the govenor arm and slowly accelerate the engine.
Somewhere better than 1/2 way open you will find the engine starts to miss and it should sound just like it is running out of fuel because that is exactly what it is doing.

Partially closing the choke restricts the amount of air that can enter the engine so it balances the lack of fuel with a lack of air.
When you engege the blades you put a big load on the engine, both physically from spinning up the deck but electrically as well due to the current draw of the PTO clutch so the engine slows down which causes the govenor to open the throttle fully which allows extra fuel to enter the engine which accelerates initally then runs out of fuel so it slows down again so the govenor allows the carb to open fullly which causes a momentary rich running ( how it accelerates ) but there is not enough fuel to maintain the faster running or the fuel passage is obstructed so not enough fuel can flow so it slows down again.

Gum ( or varnish if you like ) on the side of the float valve can cause similar symptoms as it gets stickier at higher temperatures.

 

[indiggio]

Loose carb mounting bolts can do that.
As stated earlier surging is caused by insufficient fuel being supplied to the cylinder, so the engine slows down which causes the govenor to open the throttle wider to increase the speed.
During the slower running the float bowl fills up and an opening butterfly puts a strong signal on the venturi so it sucks more fuel and accelerates, then runs out of fuel and decelerates and the whole process repeats itself at infinitum.

Surging is fuel related about 99.9% of the time.
The other 0.1 % it is a fualty govenor.
Start the mower and when it is playing up put your finger on the govenor arm and slowly accelerate the engine.
Somewhere better than 1/2 way open you will find the engine starts to miss and it should sound just like it is running out of fuel because that is exactly what it is doing.

Partially closing the choke restricts the amount of air that can enter the engine so it balances the lack of fuel with a lack of air.
When you engege the blades you put a big load on the engine, both physically from spinning up the deck but electrically as well due to the current draw of the PTO clutch so the engine slows down which causes the govenor to open the throttle fully which allows extra fuel to enter the engine which accelerates initally then runs out of fuel so it slows down again so the govenor allows the carb to open fullly which causes a momentary rich running ( how it accelerates ) but there is not enough fuel to maintain the faster running or the fuel passage is obstructed so not enough fuel can flow so it slows down again.

Gum ( or varnish if you like ) on the side of the float valve can cause similar symptoms as it gets stickier at higher temperatures.

Thanks for the dissertation on how it all works. I've never really understood how the governor works to maintain the speed of the engine during increased load.

It sounds to me like the gum/varnish may be the culprit, as it does seem to have got worse after the engine warmed up a bit.
Could it be that there's a period between cold engine/hot engine where it's most sticky, I wonder?
The reason I ask is that the other day, after running the engine for a while and it started this bogging down business, after I got the blades going the mower worked for the next hour without bogging and I was able to cut the lawn.

Thanks!

 

[bertsmobile1]

Just for an idea how decieving this "when hot" idea can be.
The landlord runs a fleet of 2000 series Cubs ( 5 now).
Some of them would run fine for an hour or so then backfire, loose power be impossible to start so we went down the things that get worse when hot route.

Ended up some 100 or so hours latter being nothing more than a plug of grass getting sucked into the fuel tank outlet.
Clean out the tanks on all of them and they have been faultless since.