Fixing a surging engine on a zero turn lawn mower with a Kohler 7000 series engine

Hi all! In today's video, I will be fixing this zero turn mower that surges very badly. I will walk through how to fix it and what to do. I am performing this fix on a Kohler 7000 series engine. Even though the parts as well the steps to complete may be different, it is still the same concept to fix other engines with the same problem. I hope you all enjoy the video!
Part number to the rebuild kit I used: Kohler 25 757 27-S

[@BradfordSmith-d1i]

This young man knows his stuff. I found this video very helpful, and informative. Nice job brother.

[@jonahssmallenginerepair]

I appreciate the kind words. I am happy to help!

[@stevegann3251]

I been searching for a good carb tear down and explaining jets and other parts ! Thank you .

[@jonahssmallenginerepair]

My pleasure. I'm glad you enjoyed it.

[@rickotte2120]

Took carb off twice. No luck. WATCHED your video and cleaned emulation tube. Wam!!! Fixed. THANK YOU

[@jimmywinterbotham5950]

Thanks for the video. My Kohler 7000 series engine began surging at idle a few weeks ago. After watching your video I decided to try to get to the emulsion tube without taking the carburetor off and it was really easy. After taking off the back "Gravely" shroud i ground down a 1/2 inch wrench to spin off the bolt holding on the float bowl, just as you showed. I then altered the outside diameter of a short, fat flathead screwdriver to get the set screw out, however the emulsion tube never came out. I generously shot carb cleaner up the carb in where I thought the emulsion tube was, put the carb back together and fired the engine back up. The surging problem was gone. THANKS!!!

[@garybarker4481]

Thank you so much ! Now I know what to do. This video is one of the best that I have ever seen. Well done ! Even the music was done right. We need information like this ! It's either fix it yourself, if you know what to do, or wait 2 months to get it fixed in the Springtime ! And it isn't cheap ! My Bad boy has this engine !

[@jonahssmallenginerepair]

Thank you for the kind words. I'm glad you enjoyed the video.

[@AriaSmith-u9k]

Nice work. Great video to follow step-by-step. Just a footnote, my choke was sticking a little bit. I pulled on the arm and it popped back into place and now swings freely.

[@toddmeyer9418]

Thanks! Cleaning the pilot jet did the trick for me. I also cleaned the emulsion tube but I think the pilot jet was my culprit. I had surging at mid and low throttle.

[@jonahssmallenginerepair]

Thank you so much! I am glad that this method was able to help you out!

[@BlugubriousMusic]

Man that before and after at the end was satisfying. Nice work

[@jonahssmallenginerepair]

Thank you! I'm glad you enjoyed it.

[@mfvarnum58]

Just finished a successful repair of my carburetor. No more surging. Thank you, sir, for the video and the rebuild kit number. I believe my papa would be proud. blessings on blessings to you!!

[@jonahssmallenginerepair]

I am so glad that your mower doesn't surge anymore. You deserve to be proud!

[@DNOWAKJR]

I made two attempts unsuccessfully to resolve the issue. Your video made me want to make one last attempt. Others use cleaner and compressed air, your use of the drill bit is what saved me. I didn’t have the bits but used a small picture hanging wire.

[@jonahssmallenginerepair]

I am glad that it is fixed. What ends up happening is corrosion gets in that jet from ethanol, and that corrosion will not go away with air or spray.

[@pedroaguiar307]

I have the same issue with my mower and will try this method. Thank you for the video.

[@jonahssmallenginerepair]

I'm glad I can help. Let me know if you need any help throughout the process, and what the end result is.

[@shaunmymudes]

Wow, this is just an awesome video, making a potentially costly and complicated repair look doable for neatly anyone. Great job and really appreciated!

[@jonahssmallenginerepair]

Thank you. I appreciate the kind words.

[@TC10394]

I am having the same issue with my Cub Cadet 😒 Engine surging for no apparent reason. Changed spark plug, oil, gas filter, air filter (no help). I was thinking, it's either carburator, bad gas or the electronic Intellipower module. Never had to clean a carburator before but will give it a try. Thanks for the helpful video!

[@jonahssmallenginerepair]

I'm glad you enjoyed it. I am not 100% sure how MTD's IntelliPower system's work, but I do know that there are electrical wires that go into the carb, which makes the carb waaay more complex than any other small engine carb. So I am going to warn you, if you take the carb apart, I would be careful.

[@deeeeeeps]

This was actually a really good video. My Kohler is brand new and runs great but ended watching the whole video even though I know how to rebuild a carb.

[@jonahssmallenginerepair]

Thank you. I am glad you enjoyed it.

[@bigsonslawncare]

Great video good information same engine on my Cub 200 hrs rolling strong.

[@richarddeboer6112]

Your a pretty smart young man ! Excellent job !

[@jonahssmallenginerepair]

Thank you!

[@rickdff62]

Nice video. FYI - The thing you were calling the "smart choke" is actually the thermostat. That black plastic piece (air vane) is technically the "smart choke". Basically, the flywheel pushes air over the "air vane" once it starts which in turn opens the choke. The thermostat does work in conjunction with the "air vane" as it will open the choke fully once then engine heats up. One last thing, my studs came out the 1st time I had the carb off too so I added thread locker to keep them in. Great job on cleaning the carburetor too. Cheers.

[@jonahssmallenginerepair]

Thank you. I'm sorry. You're correct. It is just a thermostat.

[@rickdff62]

@@jonahssmallenginerepair It's all good, just wanted to mention for clarity. I have the same engine in a 2016 Cub Cadet so I've been working on it for years. The 7000 series, at least mine, has been a great engine. Cheers.

[@toddlynn3564]

Good job young man!

[@CP-mj8wd]

Very through video thanks for sharing.

[@marcus3078]

I have this engine on my cub cadet mower. It runs fine but surges when its under load cutting and only while cutting. Turn blades off and runs smooth full throttle no problem. Im going to give this a try and see if it fixes my issue!

[@jonahssmallenginerepair]

Typically when that happens, the engine is running a little lean, so it should fix your problem. Let me know how it goes!

[@CHarris73]

My cubby zt1 ultima at full throttle acts like a spoiled child, and acts well at low throttle.

[@monotheis6889]

Been doing small engines since I discovered I had a need for speed at age 7. At age 12 or 13, I started running nitro methane from the remote controlled airplanes that always crashed, in my go-kart (SPEED!) At this point, with all the fried pistons, rings, valves etc. , I took a small engine course through 4-H club. I'm 57 now. Memories 🤔🤪

[@stevenlapham5254]

Very clear explaination/direction.... good job.... unscripted!

[@jonahssmallenginerepair]

Thank you.

[@PeterSavino-sw1uw]

The best video I've found on how to replace and rebuild carb ..great video thanks ill subscribe and watch others ..thanks pete

[@jonahssmallenginerepair]

Thank you!

[@jamessirman6622]

Excellent video. The part that you didn't show was how you double nutted the carb attaching studs. Would like to have seen. Thanks

[@DK-vx1zc]

Nice job! Great narration and videography

[@scottlocklear2062]

How did you get the tube out you actually went step by step the when u got to the problem you took carb out of the shot and brought back in the shot and it slid out. How did you do that mine is not coming out hell i had to use an easy out just to get the jet out

[@jonahssmallenginerepair]

I apologize for leaving this part out of the shot. To get the emulsion tube out, take a flat head screwdriver straight down the throat of the carb, and push down on the top of the emulsion tube with the tip of the screwdriver. If you had a hard time getting the jet out, my guess is that you will have an even harder time getting the emulsion tube out. If I were in this situation, I would try to use this method to get it out, and if I couldn't, I would just leave the emulsion tube be. Usually, it doesn't clog up as much as the jets do.

[@briandotlich472]

I wonder if you could use torch tip cleaners instead of drill bits

[@EFX21853]

Thanks for this great informational video. I have a 7 year old scag with 216 hours on it; 27hp. Just today it started surging like crazy. What irks me is this engine has seen nothing but non-ethanol 91 octane gas since day 1. How would the carb get dirty when I’m using good gas?

[@jonahssmallenginerepair]

@@EFX21853 I'm glad you enjoyed it. That's a tough question, and I am not 100% sure why, however I have some ideas. The engine could develop tiny air leaks among carb gaskets or intake manifold gaskets. and just demand a very tiny amount of additional fuel. This may also occur to that old of an engine (I'm just guessing) due to slight wear in the valves and rings, which isn't a bad thing, it may demand a slightly greater amount of fuel. If you stick with the method in the video, it should fix your problem.

[@EFX21853]

Update: My engine was surging so bad I couldn’t get it to idle at low. I put a full can of Seafoam into the tank (4 ish gallons?) and filled it up. After the tank was nearly empty, I didn’t have any improvement. I had to cut three lawns this past Saturday. When I got home, I cut the idle down, and it idled perfectly. No more surge. Pleasantly surprised!

[@jonahssmallenginerepair]

@@EFX21853 Hmm, Maybe the Seafoam slowly ate away at corrosion or debris in the jet? Nonetheless, thank you for the update and I am glad that it is working well once again.

[@ironhead782]

You don't have to take the 4 bolts completely out that holds the shroud down. The holes on the shroud are open on the bottom and all you have to do is loosen them and pull the shroud off.

[@ironhead782]

I am working on a 26 HP Kohler with the electric choke. The choke is not opening up and the engine is running rich and blowing black smoke. I can manually open the choke by moving the air vane. It runs good for a while and then starts starving for fuel at full throttle. Suggestions???

[@jonahssmallenginerepair]

@@ironhead782 To me, it seems like you have two problems. As far as the choke, there are two phases of opening the choke, the air vain, which opens the choke 40% when the engine first starts, then a thermostat, that opens it the rest of the way when the engine runs for a while. If the choke doesn't open when you first start the engine, you most likely have a problem with the air vain. You described being able to manually open the choke by moving the air vain? In order for that to work properly, the main engine shroud needs to be on, or else, the air vain won't get air blown onto it. Try putting the main engine shroud on and see if the choke opens. Also, make sure there isn't any debris (mouse nests) blocking the air vain from easily opening. As far as it starving for fuel at full throttle it sounds like maybe your carb isn't getting supplied with enough fuel. This could either be a fuel line/fuel pump issue or a carb issue. Try taking the fuel line off of the carburetor and crank over the engine to see if fuel comes out. If it does, then you may want to clean/replace your carb. If it doesn't, then maybe replace your fuel pump. Hope this helps. Let me know how it goes.

[@ironhead782]

@@jonahssmallenginerepair When I got the mower from my niece the air vane was laying on top of the voltage regulator. It wasn't even in place. I put it in place and connected the rod and then noticed the spring wasn't even there. I actually found the spring under the muffler. How it got there and didn't vibrate off is a puzzle to me. I put it all back together and that is when I noticed the choke wasn't even opening a little bit. I have one ordered and I have a rebuilt kit for the carb ordered as well. I will see what happens when I get those things installed. Thanks for getting back with me on this. I appreciate it.

[@SirtubalotTX]

Awesome video and thanks. I do want to say though I was able to fix the issue by just using a good carb cleaner a couple of times. I know that doesn't always work but definitely easy to try it first. (I may start using a little sea foam in addition). In case all of that doesn't, I now know how to do the rest.

[@jonahssmallenginerepair]

Most often, the jet needs to be drilled out because it has either corroded, or dirt has become stuck in it. Your method of spraying it with carb spray a few times may work in some cases, when there is dirt stuck, however, it may not always get rid of corrosion. My recommendation is to run ethanol free gas in your mower to prevent corrosion. Just a tip for the future. I am glad I could help!

[@SirtubalotTX]

@@jonahssmallenginerepair True that. I wasn't thinking about the Ethanol, I'll try and keep the corn out of my mower. lol

[@JJPlayz-mu8bw]

If you could, would replacing the entire carb with a new one work as well

[@jonahssmallenginerepair]

I agree and I would 100% do that... its just the price is not right, and I am not willing to go aftermarket.

[@jasontharp6702]

Thanks a ton!!

[@kc9146]

Are we ignoring the fact that this engine has a blown headgasket? You can hear it when cranking of shutting it off, that’s air whoosh noise is classic blown headgasket on a Kohler.

[@jonahssmallenginerepair]

Thanks for pointing that out. I'll check compression on it.

[@crizzotch]

Meh man! Great instructional video, with all the oops, which is great! Thank you, but Where The Heck Are Your Neoprene Gloves?! Protect your hands from chemicals.

[@TexasScout]

Dude, you don't need to pull the entire shroud to get to the carb. Just the the 5/16" screws holing the air filter cover off and then the two 10mm nuts below and that's it.

[@jonahssmallenginerepair]

Yeah, I am aware. I just wanted to get the mouse nests out from under the shroud because I knew they were in there.

[@mowerrepairshopfortscottkansas]

Grate video

[@jonahssmallenginerepair]

Thank you very much.

[@mfvarnum58]

Thanks!

[@jonahssmallenginerepair]

My pleasure! Thank you!

[@johnrencheck2283]

DUDE EVER SEE MECHANIC VIDS OF HAVING TO TAKE CAR APART TO GET TO A SIMPLE FIX I FEEL UR PAIN

[@robbarnhill9572]

5:10 mark...That is the governor, not the choke.

[@jonahssmallenginerepair]

The governor in that engine is inside the crankcase. So it is not visible without severely disassembling the engine. The linkage that leads to that thing, leads to the carburetor's choke butterfly.

[@williamalbright8878]

I always clean my air filter and pre filter after I mown the lawn and blow off entire mower

[@jonahssmallenginerepair]

I will too (most of the time). That's what I advised with this mower. It does take time to take off the shrouds though, that is done once amonrh.

[@shadmeyer7791]

Fuel pump getting weak

[@Phife_Diggy]

Ugh the Kohler's are a hunk of junk my dude

[@jonahssmallenginerepair]

These engines definitely have their fair share of problems.

[@Phife_Diggy]

@@jonahssmallenginerepair for sure hahah, I don't know if you've watched Taryl Fixes All but he's covered a lot of their faults

[@KNsmallenginerepair69]

briggs and stratton is the best

[@jonahssmallenginerepair]

@@KNsmallenginerepair69 I agree. Those briggs flathead engines are tanks. Never break, never cleaning carbs. However the briggs inteks are trash. They blow camshafts, have cheap carbs, and are just made cheaply.

[@KNsmallenginerepair69]

@@jonahssmallenginerepair true i have had to replace a camshaft in like 10 motors

[@lukemix6463]

I’ve replaced the: Carb (with an OEM kohler) Fuel pump Fuel filter Spark plugs ( I have a kohler v-twin pro series 7000 engine) Air filter Battery Blades Oil and oil filter And the damn thing STILL SURGES! I have run out of ideas. Any tips would be great, thanks!

[@jonahssmallenginerepair]

Hi Luke, If your mower is surging how the one was in my video, that means your engine is either not getting enough fuel from the carburetor's pilot jet, or your engine is getting too much air, often from a leaking gasket. I would start by taking your intake manifold off and inspect it for pinholes. If there isn't any, replace the o rings that go to the engine, and the carburetor intake gasket, and reinstall the manifold with proper torque spec. If none of this works and it is still surging, try the method of drilling out the jet, like I did in the video, but be careful, as this can either fix your problem or make it worse, depending on what size bit you use, meaning use one bit at a time, don't drill too big. If the engine still surges, reply to this comment, and we could work something out.

[@lukemix6463]

@@jonahssmallenginerepair ok I’ll try that. Thanks for the help!

[@JohnKelser-y3m]

My cub cadet was surging also.Replaced plugs and checked carb Only 30 hrs on it.reinstalled same shit .pulled apart found gskt to air cleaner didn't look right.Wasnt mating right thin at bottom Replaced both gskts. Runs great . Bottom looked like it was sucking to much air and dirt Surface should of been wider.

[@jonahssmallenginerepair]

@@JohnKelser-y3m Thank you for sharing. That's quite strange that that was the problem. My guess is Kohler made the pilot jet on the carb just rich enough to barely run right, so that when you remove the air filter (or in your case,, break its seal) the fuel mixture leans out just enough to start surging.

[@mitchellmartin6222]

Great job, young man

[@jonahssmallenginerepair]

Thank you kind sir!