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Donald, Small Engine Technician
Category: Small Engine
Satisfied Customers: 2146
Experience:  I have 25+ years of experience repairing 2 & 4 cycle engines
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My 27 HP Kohler on a SLT1554 Cub Cadet Tractor starts out

Customer Question

My 27 HP Kohler on a SLT1554 Cub Cadet Tractor starts out fine. After running for while and warming up the engine starts a repetitive surge or lope from low to high RPM. After a few more minutes the the engine stalls and will not restart. If I let it cool down for 10 or 15 minutes then it will restart OK and run for a shorter while before the same condition repeats.
I bought this Cub used earlier this year and replaced the oil, oil filter, gas filter and this improved some earlier conditions. The unit sat in a barn for several years unused before I bought it. My hunch is that the problem is related to fuel fouling or clogging in the carb.
One other symptom is that when I shut off the Cub after a normal run I get a single loud backfire. But when it stalls after the surge condition I don't get the backfire.
Any help would be appreciated. I bought this unit with only 145 hours showing and I've added 20 or so this season. Hope to keep it for a long while.
Submitted: 1 year ago.
Category: Small Engine
Expert:  Donald replied 1 year ago.

Hello Mark. Thank you for choosing Just Answer. My name is***** will be happy to assist you. Your carburetor have a fuel shut off solenoid. If your fuel shut off solenoid is faulty, it could be failing after it heats up, and either partially or fully shutting off your carburetor fuel flow.

Expert:  Donald replied 1 year ago.

Your fuel shut off solenoid should click each time you cycle your ignition switch on and off. It has a spring loaded plunger that must retract, when your ignition switch is on, to allow fuel to flow within your carburetor. Sometimes this part will fail after it reaches full operating temperature.

Expert:  Donald replied 1 year ago.

If you have some carburetor cleaner in a can, or starting fluid, spray a small burst directly into your carburetor, immediately after your engine stops running, to see if your engine will start right back up and run briefly, or if your still have to wait a few minutes before your engine will re-start.

Customer: replied 1 year ago.
Thanks for responding. I think I heard a very faint click the first time I turned key on and off. I tried another 10 times or so and did not hear a click. OK, I will run the tractor and cut some grass while I wait for the stall. And I'll respond again later after spraying the carb cleaner.
Expert:  Donald replied 1 year ago.

Thanks for letting me know. We can continue from here.

Customer: replied 1 year ago.
Hi Donald,
Update, I cut about 1/2 acre and the surging problem started. After it stalled I used the starter spray and it started up but then surged immediately so I decided to let it cool off in the shade for a while.
Also note; when I first start on a cold engine I get the surging right away but then when I load the engine by pulling out the PTO clutch knob to start the cutting deck the surge goes away. It was OK for about 20 minutes of cutting and then the surging that causes the stall started up. I did try pulling the choke out for a richer mixture but that only helped for about 20 seconds before the stall out.
Expert:  Donald replied 1 year ago.

Thank you for checking. This confirms that our problem is fuel related. There are three possibilities I would focus on.

  • Your fuel shut off solenoid. If it is not clicking after twenty minutes,it could be at fault.
  • If your fuel tank is not properly venting, your fuel flow could be stopping after twenty minutes.
  • Also, your carburetor may be in need of a really good cleaning.
Expert:  Donald replied 1 year ago.

If your fuel tank have sediments floating around inside, they can eventually settle over the outlet hole in your fuel tank, and restrict your fuel flow.

Expert:  Donald replied 1 year ago.

We can continue from here.

Customer: replied 1 year ago.
OK, stay tuned later this week. I will do some more cutting and try opening the gas tank cap to allow the air pressure to equalize. I'm sure hows to get sediments out of the tank. Do I have to remove the tank to clean it or can it be done in place?
I have one of those video cams for looking inside inside walls. I'm not sure if it is OK to use it in gasoline. Maybe a small mirror and a flashlight. But it sounds like a good carb cleaning is next and verification of the shutoff solenoid.
Expert:  Donald replied 1 year ago.

If you drain all the gas from your tank, then let it air dry, you will be able to safely use your video cam. Let's hope your fuel tank is clean inside.

Expert:  Donald replied 1 year ago.

Verify your fuel shut off solenoid first, then consider cleaning your carburetor, if needed.

Customer: replied 1 year ago.
Hi Donald,
I was super busy this past weekend and didn't get to do any of this but I did have one update. My cousin was visiting and he wanted to do something so I asked him the cut the grass. It was a nice cool day ~75 degrees and he had no problems until he disengaged the PTO. It surged only with no load. But when he was driving and the PTO engaged the loping stopped.
I think we can rule out the any dirt in the tank clogging things up. It is most likely the carb. I'm going to order a new solenoid and carb repair kit. Do you recommend anything or anyone in particular I should buy it from. Amazon and the Cub dealer have parts and I haven't checked Tractor Supply.
Customer: replied 1 year ago.
He cut for 4 hours on ~3 acres of grass with no stalling. The first day I contacted you it was about 88 degrees out so I think temperature effects the surging symptom I'm seeing.
Expert:  Donald replied 1 year ago.

Thanks for the update. Amazon is a good place to purchase your parts. You can also either purchase, or order them through your local small engine repair shop. eBay will likely have the best prices.

Customer: replied 1 year ago.
I bought a new carburetor on EBay and installed it this weekend. That fixed the problem; no more surging. I will keep the old one and clean it thoroughly and replace the solenoid if need be so that I have a spare since this tractor has so few hours on it.
I also fixed at least 3 other problems so the tractor is running tip-top for now. Thanks for all your help.