Scag/Kohler Power loss

bobframe · May 29, 2014

I use a 61" Scag Turg Tiger to mow about 3 acres at my farm. The mower is 10 years old with approximately 360 hours. Engine is a 27HP Kohler with carburetor.

I have recently noticed that the engine loses power and sputters somewhat in situations that stress the motor...like turning uphill while cutting grass or when mowing up a steep incline. While I used to observe this occasionally in the past, it seems much more common lately. If I had to guess, I'd say the engine is being starved for fuel.

Dealer thought it was fuel starvation because of the carburetor design and that a new carb ($350-400 installed) might fix it. Or it might not. A new $11,000 Scag, he assured me, will fix the problem. Indeed.

I wonder if simply cleaning the 10 year old ethanol soaked carb might solve the issue??

While I may have to spring for a new mower I thought I'd cast about for some friendly advice.

Anyone worked through this issue?

bobmisi · May 29, 2014

With only 360 hours on the mower, I would never trade it. It is better than the new ones being sold today, except the new ones have fuel injection, which is nice. I had a problem somewhat like you are having and the dealer thought it was the carb. They rebuilt it and it still did the same thing, sporadically. I changed both coil packs and the problem was solved. I think the dealer would love to get your really low hour mower on a trade for little money and resell it for a nice profit. That mower is worth good money. Find a good mechanic, not necessarily at the dealer.

bobframe · May 29, 2014

bobmisi said:
With only 360 hours on the mower, I would never trade it. It is better than the new ones being sold today, except the new ones have fuel injection, which is nice. I had a problem somewhat like you are having and the dealer thought it was the carb. They rebuilt it and it still did the same thing, sporadically. I changed both coil packs and the problem was solved. I think the dealer would love to get your really low hour mower on a trade for little money and resell it for a nice profit. That mower is worth good money. Find a good mechanic, not necessarily at the dealer.

Very helpful. Can you explain the "coil packs" to me? How expensive to replace them? Was this something that could be tested and found to be defective?

I suspect that my dealer is not a great mechanic...but I have no idea how to find a one... particularly one with access to Scag/Kohler parts. Suggestions?

bobmisi · May 29, 2014

Each cylinder has a coil that fires the spark plug. Just follow the wire attached to the spark plug and that's the coil. Not sure how to test them. Mine was sporatic. Ran good then it would act up and run badly. Shut it down and let it cool down and it would be good again. A good mechanic should be able to help you out as far as testing. I'm a shade tree mechanic, but I can usually figure out my mechanical issues, unless the piece of equipment has a computer module. Then all bets are off. Even chain saws have computers now. Cannot replace a carburetor without progamming it into the saw's computer. Good luck.

bobmisi · May 29, 2014

Each cylinder has a coil that fires the spark plug. Just follow the wire attached to the spark plug and that's the coil. Not sure how to test them. Mine was sporatic. Ran good then it would act up and run badly. Shut it down and let it cool down and it would be good again. A good mechanic should be able to help you out as far as testing. I'm a shade tree mechanic, but I can usually figure out my mechanical issues, unless the piece of equipment has a computer module. Then all bets are off. Even chain saws have computers now. Cannot replace a carburetor without progamming it into the saw's computer. Good luck. They weren't real expensive as I recall.

bilrus61 · May 29, 2014

Replace the in-line fuel filter. Even if it looks clean. I think that will solve your issue.

lilranch2001 · May 29, 2014

make sure air filter is clean, fresh is even better
use non ethanol gas, it will save carb parts

HABS1010 · May 29, 2014

Hello ,

I am having the same issues with a CASE IH DX 25E, I lose power and when it cools off it ran good enough to get it back to the garage. It is a 25hp diesel.

The RPMS would go from 1000 to 2500.

bobframe · May 30, 2014

lilranch2001 said:
make sure air filter is clean, fresh is even better
use non ethanol gas, it will save carb parts

Just had mower serviced at dealer, though I can't say whether a fresh air filter was used. In the last year or so I have switched to "real" gas...no ethanol. Still, there were 8-9 years of corn fuel run through that machine, so I guess its possible that the fuel system still suffers from the effects. That would argue for a carb overhaul or replacement.

OrangeToys · May 30, 2014

I run 3 turf tigers daily with more hours than that and I will tell you turning up hill with blades engaged takes a lot of power and is harder on the pump than the motor. Plus a new one would cost you 10-11k. your mower should last 1500-2000hrs if taken care of.