Scag Turf Tiger Won't start

bobframe

Forum Newbie
Joined
May 29, 2014
Threads
3
Messages
7
I have an (approx) 2004 Scag Turf Tiger with 61" deck that won't start. The mower has about 360 hours total (averaging around 30-40 hours per year) and is used to cut grass at my home. This non-starting issue has been going on for a couple years now and has frustrated me and the Scag dealer who seems to be at a loss. I'll give as much background as I can piece together from memory and service records. .

Episode #1: Two years ago I was mowing on the backside of my dam and the mower stalled in some thick grass on a pretty steep slope. I tried to restart it, but the mower was dead and would not turn over at all. I checked the fuses under the seat and found the bottom 20A fuse blown. I replaced the fuse and tried to start. The mower was still dead and I found the second fuse blown. I did this two more times with identical results. Hauled mower to Scag dealer and they replaced a relay somewhere and the mower ran fine.

Episode #2: Last year I was mowing, cut engine to talk to someone and the mower failed to restart. Identical symptoms to previous episode...blown fuses, no turning over, no sound, just dead fuse. Back to dealer. Again, no clear "smoking gun"...they replaced a wiring harness (#483440) and the mower ran fine.

Episode#4: A month after Episode #2, I experienced the exact same symptom...mowing like a champ, turn it off to talk, then dead. Fuse blown. Dealer changed out battery and could find nothing else wrong. Mower ran fine after this, but neither dealer nor I thought we'd really gotten to the bottom of the issue. .

Episode #5: Identical to Episodes 2&3, except the fuses were NOT blown. But mower was completely dead. I decided to let mower sit in my driveway overnight and see if a cold start gave different result. It did! So I mowed for 45 minutes, pulled it onto the trailer and hauled it to dealer. Mower would not reproduce the symptoms, it ran fine and dealer was at a loss for what to do since nothing was wrong (apparently).

Episode #6: Two days ago I ran the mower for several hours successfully, though I never turned it off until I finished working. Yesterday, I tried to start the mower cold and it was dead, no fuses blown. I happened to have a guy here who works for a big landscape company and he tried to trouble shoot the mower. Battery tested at 13.5V. There does seem to be a faint "clicking" sound when the ignition was turned on. The guy held a screwdriver across the starter terminals and got the motor to turn over, but the exhaust was very "gassy" smelling and I could see what appeared to be unburned gas. It sounded as though the engine was turning over but not firing...which I thought explained the visible and gassy exhaust.

Any suggestions?

Thanks so much for sharing what you know,

Bob
 
Last edited:

bertsmobile1

Lawn Royalty
Joined
Nov 29, 2014
Threads
64
Messages
24,647
There are two lots of "safety " circuits on your mower.
One stops the starter from cranking
The other stops the plug from firing.
Shorting out the solenoid defeats the first but not the second, hence the unburned fuel smell.

There should be 2 small terminals on the starter solenoid.
One is + the other -
The + comes from the ignition switch "S" terminal then goes to the PTO switch and some times the parking brake or lap controls then down to the starter solenoid
The - goes through a convoluted path involving the seat switch, PTO switch & lap controls in varying combinations.

So take a voltage reading from each of the small terminals to earth with the key in the start position.
The one that goes 12V is the +
If you get 12V between the terminal & earth then try between the two terminals.
No voltage then check for continuity betwen the - and ground.
From here on it is a matter of working backwards through all of the switchs & relays to find the one that is gving you grief.
I have a box full of jumper leads with 2 Male or 2 female terminals on them which I use to bypass each switch, one at a time till the culprit is found.
Remember some switches will make/break both a + connection and a earth connection and some of the earth connections are also for turning off the spark.
 

bobframe

Forum Newbie
Joined
May 29, 2014
Threads
3
Messages
7
There are two lots of "safety " circuits on your mower.
One stops the starter from cranking
The other stops the plug from firing.
Shorting out the solenoid defeats the first but not the second, hence the unburned fuel smell.

There should be 2 small terminals on the starter solenoid.
One is + the other -
The + comes from the ignition switch "S" terminal then goes to the PTO switch and some times the parking brake or lap controls then down to the starter solenoid
The - goes through a convoluted path involving the seat switch, PTO switch & lap controls in varying combinations.

So take a voltage reading from each of the small terminals to earth with the key in the start position.
The one that goes 12V is the +
If you get 12V between the terminal & earth then try between the two terminals.
No voltage then check for continuity betwen the - and ground.
From here on it is a matter of working backwards through all of the switchs & relays to find the one that is gving you grief.
I have a box full of jumper leads with 2 Male or 2 female terminals on them which I use to bypass each switch, one at a time till the culprit is found.
Remember some switches will make/break both a + connection and a earth connection and some of the earth connections are also for turning off the spark.

Very helpful. Its not likely that I will do the repair myself, but this gives me a way to ensure that the dealer is using a logical troubleshooting procedure.
 

bertsmobile1

Lawn Royalty
Joined
Nov 29, 2014
Threads
64
Messages
24,647
Bob,
Don't be so down on yourself.
It is really quite easy.
All you need is some wires with spade terminals on them and a multimeter.
You check to see weather a switch ( disconneted from the loom) is open or closed when the item is on or off then jump or leave unconnected the terminals on the loom plug.
It is not hard to do but is a bit time consumming so can be a very expensive shop repair if they charge actual time spent and not scheduled hours.

The owners manual tells you which switches to jump.
Lap controls in brake position , PTO off, parking brake ono then turn key to start.
 

bobframe

Forum Newbie
Joined
May 29, 2014
Threads
3
Messages
7
Bob,
Don't be so down on yourself.
It is really quite easy.
All you need is some wires with spade terminals on them and a multimeter.
You check to see weather a switch ( disconneted from the loom) is open or closed when the item is on or off then jump or leave unconnected the terminals on the loom plug.
It is not hard to do but is a bit time consumming so can be a very expensive shop repair if they charge actual time spent and not scheduled hours.

The owners manual tells you which switches to jump.
Lap controls in brake position , PTO off, parking brake ono then turn key to start.

I'm sure that if someone could walk me through it it would be fairly easy. But I don't have time...grass needs cutting and leaves need mulching NOW. I do appreciate your encouragement, but to start trying to figure this all out now would just take me too much time. BTW, I also found out my tractor won't start...gotta deal with that Monday as well.

However, knowing that there is a logical process to follow makes me more confident that I can ask the right questions of the dealer.

Again, many thanks!!
 

bobframe

Forum Newbie
Joined
May 29, 2014
Threads
3
Messages
7
UPDATE.

I called the Scag dealer this morning and described my current status. He began troubleshooting over the phone and had me turn the key to Start and hold it there while I pulled the PTO switch. The mower immediately started and ran like a new mower. After turning mower off, the mower restarted like new.

PTO switch bad?

Dealer thought so, I'm headed to shop to have that switch replaced.

My last bit of work with the mower was mulching heavy piles of leaves...maybe some debris in the PTO switch was cleared out when we started the mower?

Anyway, I feel like we may have identified the culprit...could the PTO switch be acting intermittently?
 
Last edited:

Micah Haarhoff

Well-Known Member
Joined
Sep 17, 2015
Threads
14
Messages
272
Yes it can. Mine did that a few years ago.

You should replace the PTO switch yourself instead of paying him to do it unless it was under warranty. :)
 

bobframe

Forum Newbie
Joined
May 29, 2014
Threads
3
Messages
7
Next time I may. He only charged me $20 to install it, so I think he treated me fairly. IF it fixes the issue.

The mower runs like a million bucks...mulched leaves for three hours and at the end I turned machine off and on a couple of times to see if my restart problem is solved. It appears to be fixed.

Thanks for the help guys.

Bob
 

bertsmobile1

Lawn Royalty
Joined
Nov 29, 2014
Threads
64
Messages
24,647
That is my standard fitting fee if a customer supplies the part so looks reasonable to me.
 
Top