Scag Tiger Cub engine problem, need help

[royalton10]

I have a Scag Tiger Cub that I purchased in 2003, it has 360 hours, I mow 1 acre in central Ohio.
It is STC48A-19KA with a serial number 8402154.

For several years, the engine cuts out intermittently. It does not do it every time I mow. It seems to do it the most often when the ground is very wet, and especially when making turns. I have to baby the engine, turn very slowly, and mow going very, very slow to keep engine running at all. If I can keep it going for 10 minutes, it seems to get much better.

I took it to a different dealer this spring. (dealer I bought it from no longer sells Scag), they could not find anything. It seemed to be much better for several months once I used a real Kawasaki air filter, not a generic. I had to get the correct air filter for the internally vented carburetor. I am using a Kawasaki air filter, 11029-7002

Now with the last mow of Nov 9, ground was wet, and the engine cut out multiple times.

I am thinking it is some kind of electrical issue, perhaps in conjunction with the turning handle bars.

Help would greatly be appreciated.

Doug

 

[Mad Mackie]

Hi Doug,
I have a few questions and several items to check.
How do you clean your machine? Do you power wash it?
How old is the battery?
Have you checked the battery and other ground connections that are on one of the engine mounting bolts?
Have you checked the positive battery connections and the cable connections on the start solenoid?
Do you have and or know how to use a multimeter?
Has anyone made any electrical system changes on your machine?
What is the part number on the interlock module?
Items to check:
Does the seat move any while making turns during machine operation?
There is a switch that is under the seat that is mounted into the machine frame that can be problematic. I have replaced the seat switch twice on my machine.
You can easily check each safety circuit on the machine if performed in correct order.
I have a later model Tiger Cub, but the electrical systems are similar. Tomorrow I will go thru a safety system check on my machine and make a list of conditions that you can use to perform a check of each safety circuit on your machine.
Later
Mad Mackie in CT

 

[royalton10]

Hi Doug,
I have a few questions and several items to check.

How do you clean your machine? by air hose
Do you power wash it? yes, but only a few times a year; leave running when I do this.
How old is the battery? 2.5 years
Have you checked the battery and other ground connections that are on one of the engine mounting bolts? not yet
Have you checked the positive battery connections and the cable connections on the start solenoid? not yet
Do you have and or know how to use a multimeter? Have one, know how to use, but give me specifics for each step
Has anyone made any electrical system changes on your machine? no
What is the part number on the interlock module? I will get that

Items to check:
Does the seat move any while making turns during machine operation? No, but I will drive it when it warms up to be
sure.

There is a switch that is under the seat that is mounted into the machine frame that can be problematic. I have replaced the seat switch twice on my machine.
You can easily check each safety circuit on the machine if performed in correct order.
I have a later model Tiger Cub, but the electrical systems are similar. Tomorrow I will go thru a safety system check on my machine and make a list of conditions that you can use to perform a check of each safety circuit on your machine.
Later
Mad Mackie in CT

Mad Mackie,

I am impressed with your post. See answers above. Thanks. Looking forward to your list.

Thanks!

Doug

 

[royalton10]

Mad Mackie,

I was able to do a few things on your list tonight.

The engine ground was tight. However, I removed the ground and wire brushed both wires that were attached to bolt attaching engine to frame. The bolt did have some dirt on it as it is very close to where oil filter screws it. Bolt wire brushed, bolt retightened.

Removed both leads from the battery and wire brushed post and the 2 bolts. Also installed new spark plugs. While I was doing all this I changed oil and filter as well.

Here is one more issue as well. There were a few times I could not keep engine running, it died. I tried to restart by choking. Difficult to restart and flames were coming out of exhaust.

Did not check starter solenoid connection yet.

Here is the interlock module number - 482313-cpm lot #0503.

Mowed leaves before the above was done. No issues.

Thanks again for all you are doing to help me, much appreciated!!

Doug

 

[Mad Mackie]

Hi Doug,
Read your thread and I've been thinking about you problem. I've replaced the ignition coils on both a 17 and a 19 Kawi and I also noted that the spark plug gap was changed to .025" on a note that was included with the replacement coils.
Not sure if this is your situation however.
I have a jumper that I use to bypass the seat switch so I can run the machine with the deck running and have the seat lifted up giving me access to the battery so I can check the battery voltage in three different conditions, voltage engine not running, voltage engine running at full throttle, and full throttle with the PTO on. I find that a properly operating charging system with a fully charged battery will have 12.6VDC about, engine running at full throttle for several minutes 14.3-14.5 VDC, and with PTO on the voltage generally drops to 13.6-13.8 VDC.
I you perform this check, place the machine on an area that is safe, drop the deck down your normal height, and mostly keep you feet away from the deck!!!!!!!!!
I'm also thinking that you may possibly have a fuel delivery problem.
But for the safety circuit checks, do a normal startup of the engine, with the parking brake still on, cycle each travel lever in and back out one at a time. The engine should start to quit as each lever is cycled.
With the parking brake off and levers out, lift yourself up off the seat momentarily and the engine should start to quit as you do this. Performing these checks will let you know if the safety circuit switches and the interlock module are working properly. Generally if the engine will crank and start, these circuits are operating properly.
Mad Mackie in CT

 

[Mad Mackie]

Hi again Doug,
As for cleaning mowing machine in general, as most or all machines of this type have what I call an "open" electrical system as compared to cars and trucks which have what I call "sealed" electrical systems. None of the switches nor any electrical connections are sealed and when washing these machines with water pressure from a garden or a pressure washer, water can and will get into switches and connections and also into bearings such as deck spindles, pulleys and wheel bearings causing problems.
I know that lots of operators and dealers both use pressure washers to clean machines, some get away with it and some don't!!! I recommend that no water under pressure be used to clean mowers, however just my opinion having been a mechanic since the mid 50s from bicycles to corp jets!!!
Mad Mackie in CT:laughing::biggrin::smile:

 

[royalton10]

Mad Mackie,

Thanks for your suggestions. Any chance you can post a picture of your jumper?

You offer it could be a fuel delivery problem. Do I drain each tank and then examine the fuel pickup line? How do I access that pickup line, exactly where is it?

I will do the safety steps you outline.

Thanks!

Doug

 

[Mad Mackie]

Hi Doug,
I looked for the jumper but didn't find it, however it may be in one my mobile tool boxes in my trailer. If not I'll make up another and photo it for you. Was doing cleanup today, 4.2 hours on the machine, more to do tomorrow and Saturday then I will put the Scag in storage, maybe!!!!! The stinking leaves just keep on coming!!!
Mad Mackie in CT

 

[Mad Mackie]

Hi Doug,
I've been straight out for three days, but I'll get some photos for you of the seat switch jumper as I did find it in my mobile tool box.

 

[royalton10]

Mad Mackie,

Sorry to trouble but I am having the same problems as detailed in the early parts of this thread. Ground is very wet after nearly 3" of rain in the past week.

Having trouble keeping the engine going, I have to go slower and slower. This week it finally just quit. It has done that twice. Is it possible that coil or coils are bad. How do I test that?

Last fall I took the mower to my local Scag dealer. They redid the ground wire from battery to the engine. Last redid the wiring harness connection that connects to the engine in a lug.

Any more ideas? I did perform the safety tests you mention, minus the jumper while mower is running. No issues, all is fine there.

Just would like to get this solved and resolved. I am sure mowing season is in full force for you in the NE by now.

Thansk!!

Doug