Scag Tiger Cub blowing 20 amp fuse

ILENGINE

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Guys I have a problem, that is giving me and the customer (commercial cutter) fits. I am working on a Scag that is blowing the main 20 amp fuse, which also kills the engine. The mower will run from 20-45 minutes between blowing fuses. When it blows the fuse, you can jump of the seat, and replace the fuse and then go back to mowing until it blows the fuse again, then repeat the above and mow some more. Any ideas to what could be the problem.
 

TheCaffeinatedOne

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Just a wild thought...

Is the battery showing an overcharge state when the motor is running? I was thinking dead voltage regulator and too much juice when the motor is working hard.
 

Mad Mackie

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A few thoughts and suggestions;
Get the model and serial numbers from the machine, go to the Scag website, on left side click on manuals, the wiring diagrams are in the operators manuals.
When you say running, is this with the PTO switch in the on position, the deck turning and the travel levers pulled in????
With many machines to include my Tiger Cub, I have had to disconnect and clean the electrical connectors.
Have you checked the electric clutch for continuity and shorting??
Check the path of the clutch wiring harness as it is close to the belts.
What is the charging system voltage? What does this voltage do while the machine is in operation as time gets close to the fuse blowing?
Check the grounds that are connected to the engine mounting bolt.
Condition of the fuse holder itself?
Chaffing wires?
Key switch?
All battery power comes from the battery side of the start solenoid, to the engine harness adapter, to the 20 amp fuse, to the B terminal on the key switch. It also splits off to the start circuit relay that is usually mounted under the same panel with the key switch and the PTO switch.
Basicly when the engine is running, PTO on, deck turning, the major player in the system that draws amperage is the electrical clutch. I have had PTO switches and key switches give me grief at times.
Mad Mackie in CT
 
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chance123

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I have been having the same exact problem with all the Scag Turf Tigers. After some phone yak with the dealer they have found that the Warner clutch has occasional spikes in the power requirement. I was autherized to try a 25a fuse. That was 2 weeks ago and no problems since. There should soon be a bulliton on this if it hasn't already
 

ILENGINE

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I have been having the same exact problem with all the Scag Turf Tigers. After some phone yak with the dealer they have found that the Warner clutch has occasional spikes in the power requirement. I was autherized to try a 25a fuse. That was 2 weeks ago and no problems since. There should soon be a bulliton on this if it hasn't already
I posted this for a little exercise. The truth of the problem was the Ogura clutch had an intermittent short when it got hot. Since this was for a commercial cutter, that really needed to use the mower, I wired a 15 A fuse holder into the hot wire for the electric clutch, to narrow down the posibilities, and it would blow that fuse instead of the main 20A fuse. Replaced the electric clutch yesterday, and when I removed the clutch found that there was also a bearing freezing up in the clutch. At the very end before I replaced the clutch, it would blow the fuse on engagement of the clutch.



Continuity checks on the clutch showed, .5 ohms instead of the 3.5 that it was supposed to have, with a continuity to ground short. clutch would pass all test procedures when cold.
 

Mad Mackie

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Good to know, Turf Tigers have a stronger clutch at 350 FTLBs as compared to Tiger Cubs and Tiger Cats at 250FTLBs and no doubt operate at higher amperage. I just repowered my Tiger Cub from a 26 B&S ELS twin to a 30 B&S Pro Turf as the 26 was loosing compression in the left cylinder. The voltage regulator that was on the new engine failed at 4.3 hours and I installed the VR from the old engine while I got a new VR on warranty. I checked the voltage and the old VR system voltage was 14.4 VDC but the new VR system voltage is 14.1 VDC which is below the spec for B&S charging systems in the 10-16 Amp range.
When the voltage is less then the amps go up with the same power requirement.
Mad Mackie in CT
 

Mad Mackie

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I posted this for a little exercise. The truth of the problem was the Ogura clutch had an intermittent short when it got hot. Since this was for a commercial cutter, that really needed to use the mower, I wired a 15 A fuse holder into the hot wire for the electric clutch, to narrow down the posibilities, and it would blow that fuse instead of the main 20A fuse. Replaced the electric clutch yesterday, and when I removed the clutch found that there was also a bearing freezing up in the clutch. At the very end before I replaced the clutch, it would blow the fuse on engagement of the clutch.



Continuity checks on the clutch showed, .5 ohms instead of the 3.5 that it was supposed to have, with a continuity to ground short. clutch would pass all test procedures when cold.
You gotta catch them when they are hot!! Which isn't always easy to do!!! Good job!!!
Mad Mackie in CT
 
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