# Cub Cadet surging/hunting, only runs on full choke,even after new carb



## cpk (Jan 1, 2020)

Hi gang. I have a question/problem I'm hoping someone can help with. I have a 1 year old Cub Cadet 2x24 I bought used after only 1 season of use. I drained the old fuel and filled it with high octane, ethanol free fuel. When I ran it, it would surge/hunt with the choke off. I took off the carb, sprayed with Gumout, took off the jet and sprayed it with Gumout, took a small wire and cleaned out the jet and all the little holes with it, cleaned the bowl, then put it all back. It still surged but then also backfired. I purchased a new carb for it (this model is a Powermore 670-wub engine and only OEM carbs exist for it) and put it on last night with new gaskets. Again, same problem: only runs on full choke and surges on half choke and dies with the choke off. Any ideas on what's going on here?


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## Kiss4aFrog (Nov 3, 2013)

:welcome: to SBF cpk

Have you checked the spark plug for gap, insulator cracking and general appearance ? You likely have a carb issue but a new plug would be cheap insurance before going through the trouble of sending this one back for a replacement. The problem is new doesn't always mean good.

.


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## vinnycom (Nov 6, 2017)

it's running lean. , why? idk. u got to much air or not enough fuel for the fuel mix ratio . u seemed to do obvious fix. u probably need to change the air fuel mix but i dont think u can on that carb. bore out the jet little or buy a bigger one


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## GustoGuy (Nov 19, 2012)

cpk said:


> Hi gang. I have a question/problem I'm hoping someone can help with. I have a 1 year old Cub Cadet 2x24 I bought used after only 1 season of use. I drained the old fuel and filled it with high octane, ethanol free fuel. When I ran it, it would surge/hunt with the choke off. I took off the carb, sprayed with Gumout, took off the jet and sprayed it with Gumout, took a small wire and cleaned out the jet and all the little holes with it, cleaned the bowl, then put it all back. It still surged but then also backfired. I purchased a new carb for it (this model is a Powermore 670-wub engine and only OEM carbs exist for it) and put it on last night with new gaskets. Again, same problem: only runs on full choke and surges on half choke and dies with the choke off. Any ideas on what's going on here?


The new engines are made to run really lean to reduce hydrocarbon emissions. Unfortunately, this makes them more prone to running extra lean which means surging and sometimes even stalling. Also, check the base of the carburetor and where the carburetor attaches to the airbox to see if it is making a good seal since even a tiny air leak could affect the engines running. If you can achieve a stable and smooth running engine by introducing some choke you will need to enrich the fuel/air mixture by hogging out the jet a little bit or simply buying a bigger main jet. I have a Predator 212cc on two snowblowers and I enlarged the hole in the main jet and they both work great when it is cold.


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## Mike C. (Jan 28, 2016)

I looked up the parts diagram for that engine and noticed something interesting in the parts list for that carburetor-it lists a "mixture screw".


Does that carb actually have adjustable idle mixture or,as I suspect,it's a tamper-proof setup like the other Honda clones?


I would check the governor system and make sure the small throttle return spring is attached correctly and not stretched/deformed.


The throttle return spring came off the carb on my HF Greyhound engine and it had a tendency to surge.


Check that clamp on governor arm is tight and make sure governor is adjusted/operating correctly-no slop.


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## RedOctobyr (Mar 2, 2014)

Welcome to the forum! Sounds like you've done the usual suggestions. 

I would check for air leaks around the carb, where it mounts to the engine. With the engine running, you can spray something flammable (like carb cleaner) around the carb/engine interface & gasket. Don't accidentally get it into the carb's intake (using a spray straw helps). If the engine's sound changes while spraying around that gasket, then you have an air leak, which is letting raw air into the engine, making your mixture too-lean. 

You used new gaskets, so this is rather unlikely, but it's easy enough to check. 

With a new carb, an air leak around the throttle shaft through the carb is also unlikely, but possible. 

Since it's a used machine, are you certain the carb's throttle and governor linkages are attached correctly? Admittedly, it definitely sounds like you're running lean, since it dies with no choke, rather than simply surging. If you hold the throttle plate open, will it still die with the choke off? 

As others have said, you may need to open the main jet's orifice slightly. You can use micro-drills for this, or torch tip cleaners also work. Since you've bought a new carb, you could modify the original jet, and still have the ability to go back to stock, by using the new carb's jet. Only make a small change at a time, though, then test it, since you can't put the metal back  

Does it make good power when you have the choke on? The backfiring seems interesting; is it still doing that with the new carb? 

If there *is* any mixture adjustment available, as Mike C saw, that would be preferable, of course.


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## Mike C. (Jan 28, 2016)

I'd careful about what Mike C. says because it appears he's as blind as a bat-somehow I didn't notice the part where it says it will only run on "full choke".I would say the governor is not involved with the surging in that case.I need coffee.


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## JLawrence08648 (Jan 15, 2017)

Follow everyone's advice here, all great, nothing incorrect said, nothing else but generally for that problem it goes back to the carb. Try soaking the carb in Berrymans carb dunk carb cleaner tank, spray a carb cleaner in the holes, use a welding torch tip cleaner, remove the Welch plug if you have one, drain the gas in a 2l clear soda bottle looking for cloudiness, discoloration, and water on the bottom.


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## RC20 (Dec 4, 2019)

I am not sure where CARB cleaner got a repautio0j as a thing to spray into a carb. Ergh, and then you are bearing the stuff that comes out. Just because it will burn, DOES NOT MEAN ITS A GOOD IDEA!


Try an unlit propane torch, Propane and MAPP burns well and right and burns cleanly.


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## vinnycom (Nov 6, 2017)

RC20 said:


> I am not sure where CARB cleaner got a repautio0j as a thing to spray into a carb. Ergh, and then you are bearing the stuff that comes out. Just because it will burn, DOES NOT MEAN ITS A GOOD IDEA!
> 
> 
> Try an unlit propane torch, Propane and MAPP burns well and right and burns cleanly.


easier to spray a flammable liquid down the throat of a carb than trying to use propane, not everyone has a bottle of propane/mapp gas but we all have some kind of flammable spray in our garage. this method has been around since the invention of the combustion engine(spraying a flammable liquid into a carb)

its all good for the short amount of time we are using it for, these simple motors arent as delicate as some may think


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## 2.137269 (Nov 15, 2019)

cpk said:


> Hi gang. I have a question/problem I'm hoping someone can help with. I have a 1 year old Cub Cadet 2x24 I bought used after only 1 season of use. I drained the old fuel and filled it with high octane, ethanol free fuel. When I ran it, it would surge/hunt with the choke off. I took off the carb, sprayed with Gumout, took off the jet and sprayed it with Gumout, took a small wire and cleaned out the jet and all the little holes with it, cleaned the bowl, then put it all back. It still surged but then also backfired. I purchased a new carb for it (this model is a Powermore 670-wub engine and only OEM carbs exist for it) and put it on last night with new gaskets. Again, same problem: only runs on full choke and surges on half choke and dies with the choke off. Any ideas on what's going on here?


items to check
is there a screw in gas filter as a part of the hose adapter at the tank? is it clean?

did you check the hose itself for being collapsed internally . 
if either is gummed up or bad you could be not getting enough gas into the carb making for a lean condition.


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## cpk (Jan 1, 2020)

Thanks for the suggestions, guys. I put in a new spark plug and the issue is the same. I'm going to pull off the tank and check it out as well as the line from there to the carb. I'll report back what I find.


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## cpk (Jan 1, 2020)

Contaminated fuel seems the culprit, and I have no idea how it happened. I drained all fuel from the tank with a fluid extractor after I bought it and used high octane, ethanol free fuel in it after. It was a new gas can so maybe something was in it that contaminated it somehow, but with plastic cans that's less likely to happen.

The contaminated fuel had little reddish/yellowish globule-like particles in it that I've never seen before. I had used some Gumout carb cleaner fuel additive when I first noticed it surging and the globules look similar


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## cpk (Jan 1, 2020)

Stupid fat fingers...

The globules looked similar in color to the Gumout so maybe this was the source of the contamination. 

It seems I had 2 issues: a carb that needed replacing and contaminated fuel. The bad fuel was removed, fresh gas put in and I ran it for about 20 minutes on no choke. It was hunting/surging at first but that cleared up after 5-7 minutes of runtime. After 20 minutes I stopped it, waited an hour and started it cold...ran like a champ. Just in time since a snowstorm is heading this way this weekend.

Thanks for the input, fellas. I'm hoping this follow up will help some others down the road.


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## classiccat (Mar 1, 2014)

When you pumped your E0, did you put the 1st gallon or 2 in your vehicle to purge the shared pump line of E10 remnants?


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## cpk (Jan 1, 2020)

classiccat said:


> When you pumped your E0, did you put the 1st gallon or 2 in your vehicle to purge the shared pump line of E10 remnants?


Straight to the can baby. Even if it was straight E10, it doesn't explain the globule-like crap in it. It really was some weird looking stuff. I wish I would have taken a picture of it.


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## classiccat (Mar 1, 2014)

cpk said:


> Straight to the can baby. Even if it was straight E10, it doesn't explain the globule-like crap in it. It really was some weird looking stuff. I wish I would have taken a picture of it.


the guy that owned the K181 tank that was harboring this mess (ethanol/water gel) supposedly only used E0. I'm guessing he also went straight to the can with it as well!


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## Space Gravy (Dec 15, 2020)

cpk said:


> Hi gang. I have a question/problem I'm hoping someone can help with. I have a 1 year old Cub Cadet 2x24 I bought used after only 1 season of use. I drained the old fuel and filled it with high octane, ethanol free fuel. When I ran it, it would surge/hunt with the choke off. I took off the carb, sprayed with Gumout, took off the jet and sprayed it with Gumout, took a small wire and cleaned out the jet and all the little holes with it, cleaned the bowl, then put it all back. It still surged but then also backfired. I purchased a new carb for it (this model is a Powermore 670-wub engine and only OEM carbs exist for it) and put it on last night with new gaskets. Again, same problem: only runs on full choke and surges on half choke and dies with the choke off. Any ideas on what's going on here?


Others have mentioned it but check that spark plug and gap. Also, if you still have the old carb, did you remove the float and clean the little "needle" as well? Do you have access to an air compressor? I always use a blowgun to get rid of excess carb cleaner overspray as well as blowing out every inlet and outlet on the carb and the fuel line. Last but not least, if your unit has an air filter, check that because it can definitely cause problems if its gunked up.


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## 140278 (Aug 27, 2020)

doubt very much the op will see your post, he has been gone mia for 11 months after 5 posts


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