View Full Version : Kohler Command 14 OHV surging and backfiring after cleaning carb

04-28-2007, 09:04 PM
:cry: I have a Kohler Command CV14S that was running fine until I used some GumOut carb cleaner on it. It started surging a few minutes after and backfiring (pre detonation maybe?) and now it wont run without the up and down surging/popping. It starts fine, but won't run smoothly as it did before... Could I have fouled the carb? I have checked all the fuel related lines and found one cracked that leads from the fuel bowl to the head, so I repaired that one, checked fuel filter/flow from the tank, but the surging/detonation still remains...I bought this unit used, and ran the engine for a full 10-15 min's while deciding to buy it, it was only after I got it home and changed the oil, plug, and sprayed the carb cleaner in it that these symptoms appeared....the new plug is the same one as orig. equip. and gapped properly (.040).....any help appreciated!...

04-28-2007, 09:09 PM
Did you have the carb. off and apart ?

04-28-2007, 10:57 PM
Thanks for the swift reply!...no I have not removed the carb..(and hope I won't have to..)..I bought this lawn tractor with the Kohler...as I said, started the motor at the sellers while debating whether to buy the tractor and it ran fine...got it home and it ran fine...then changed the oil...new plug...ran fine...then a few quick sprays of carb cleaner with the engine at about 3/4 throttle..seemed to bog down a little as usual while burning off the carb cleaner then returned to previous rpm...then shut it off and returned 20 mins. later ...started it up to put it away and the engine no longer ran smoothly...starts right up...no smoke...but won't run at a constant rpm...surging rhythmically up and down and popping occaisionally...really wierd...

04-28-2007, 11:34 PM
How's the breather line? I'm talking about this shaped black rubber tube runs from the carb into the valve cover, if that's cracked or badly corroded it could use replacing, might fix the problem. Something about there needs to be a constant vacuum on that breather tube at top rpm or it won't run right.

On my 15hp vert.shaft it's on the front of the engine...

04-28-2007, 11:45 PM
Start it up and position the throttle where it hunts the most then slowly start applying the choke. If the hunt goes away and it smooths out take the carb. off then tear it down and spray (any brand but Gumout) carb. cleaner through all ports, Passages and jets then re-assemble.

Bill Kapaun
04-29-2007, 02:11 AM
If this unit sat over the winter, possibly some water condensed in the tank. While moving it around, a bit of the water on the tank bottom may get in the fuel line and on to the carb bowl, where drops get picked up on a random basis.
I would try draining the tank and refilling with fresh gas. You may also want to replace the fuel filter with the proper KOHLER filter. Don't substitute.

04-29-2007, 11:19 AM
Thanks again for the swift replies...This unit did sit (I have no idea how long) and the gas that was in it may be contaminated...it's a good thought...what about Dry Gas....instead of draining the tank, as I just added about 2 gals. fresh fuel? I added fresh gas on the way home from buying the unit, but as I said it was running fine at that point...and I didn't think of the possibility of water in the fuel because it seemed to be running SO well....but it is possible that some water could now be contaminating the fuel....and how does one dispose of 2+ gals. of contaminated gas?? topsites, the breather line was cracked at the connector, and I recut it and re attached....Bill what would be the reason for not replacing the fuel filter with just an ordinary fuel filter? (Briggs, Honda,Husky, whatever)..aren't they all basically the same?...I have replaced several fuel filters in my time and they all appear to be constructed the same way, element wise......I never really thought there was a difference..also is there any way carb cleaner can go bad??... but, as one sprays it through the air cleaner/choke port, isn't it going directly to the combustion chamber and not passing "Go"?...therefore not contaminating the fuel bowl?? or carb jets? ;) As it's Sunday, I may try to drain the fuel bowl and add some DryGas to the fuel, but first I'll try manipulating the choke as Restrorob suggests...I still can't imagine it's anything too serious that would require tearing down the carb...as this thing was running SO well, and appears to have very few hours on it...THAT was the reason I jumped at buying it!!!:realmad:

04-29-2007, 12:46 PM
Bouncing down the road to your house could have stirred up trash/water in the float bowl and now sucked it into the main jet.

Not sure what the deal is on the filters, I've been using aftermarkets for years on every thing.

Bill Kapaun
04-29-2007, 04:51 PM
"Not sure what the deal is on the filters, I've been using aftermarkets for years on every thing."

On another tractor forum, there have been a couple instances of Kohlers not starting and/or running poorly with non OEM filters.
I think it might be a case where a gravity fed engine had a filter for a fuel pump engine installed???
The filters have different micron ratings.

04-29-2007, 11:31 PM
Micron ratings only would refer to particle size..not flow rate of fuel..and filters are designed to be passive and not cause any restriction in fuel line flow rate..unless they're clogged of course..the good news is that my situation has apparently been cured..I changed the fuel filter,(to a no name I had lying around) and drained the fuel lines while doing so, added about 3.5 oz. of Isopropyl type Drygas to the tank and agitated the gas, then restarted the engine and after about 60 seconds my symptoms disappeared, and the engine returned to it's surge free operation. I then went out and cut the front and side lawns (about 45mins. worth of mowing) without an issue. I'm guessing that there WAS some water in the fuel bowl/lines/tank and that, coupled with the leaking breather line, caused my problems. You guys called it right and saved me quite a bit of aggravation, and for that I'd like to say a sincere thanks. This is a great forum, and does a lot to bolster my faith, once again, in the Internet's ability to foster human interaction and problem solving.:usflag: :clapping:
The next question I have is whether I can adjust the top speed of this engine. Is it just a screw adjustment, or is there an electronic governor on this engine. It's kind of hard to see the bottom of the fuel bowl the way this engine is packed in the chassis. It would be nice to have 500 or so more rpm at the top end of the throttle adjustment before the choke kicks in.. Thanks again to all for your support- :drinkup:

04-30-2007, 07:55 AM
Here Ya go.....


04-30-2007, 02:00 PM
Thanks again, that's great, now If I have room to reach all that it will be nice! Does the pencil go in the "sight hole" there? Also, what's your take on oils?..Kohler recommends straight 30, my parts guy says 10w30 will quiet the valves more, another mechanic I know says use Kohler branded oils, SAE30...regards- and many thanks yet again!

Bill Kapaun
04-30-2007, 02:23 PM
"Kohler recommends straight 30"

04-30-2007, 02:50 PM
The sticker on my Kohler CV14S housing says : Summer use SAE 30
Winter use 5W30
SAE 30 is what I refer to as straight 30..no prefix (5W, 10W)...perhaps that's not what is referred to as "straight" 30??

Bill Kapaun
04-30-2007, 03:58 PM
That's interesting?
Kohlers have hydraulic lifters and have recommended multi-weight oils like in the owners manual link I posted above.

04-30-2007, 07:21 PM
Does the pencil go in the "sight hole" there?

Yes, Thats what step 3 states. Thats to keep the throttle assembly aligned while adjusting.


Bill is right about ALL Command engines requiring NOTHING but 10W30 oil for the temps listed. Below is the chart from the Kohler Factory Service Manual CV11 thru CV16 also. All I can figure is your engine had the wrong decal installed from the factory or part is missing.


04-30-2007, 10:51 PM
Well you guys have the manuals..but this sticker is all there, and clearly says "summer use SAE 30"...I'll post a pic for you tommorrow just so you can see I ain't making it up...but I apreciate all your combined knowledge...the throttle adjustment went off without a hitch...speed range is much more usable now, and I'll use 10W30 in it from now on..:drinkup:

05-01-2007, 01:25 AM
my mower was doing this after i messed with the carb, and my uncle who is a head mechanic for fedex said get in a not dusty area, take off the air filter, rev it up as high as i can and then put my hand on the intake to suddenly seal it off and create suction.

worked and it instantly ran better.

he said that when you mess with the carb at all 90% of the time its cuz a small particle got stuck in the jet or somewhere and this high vacuum usually gets it free.

he said do it in this order:
first try tapping the float bowl while running.

then try the described vacuum method above.

then last resort take the carb off/apart and thouroghly clean inside and out with carb cleaner, making sure to get in all the holes.

05-01-2007, 10:24 AM
The other thing that comes to mind is that spring that hooks up to the automatic throttle adjuster, forget what it's called but it's a lever that likes to move back-and-forth sometimes even when the throttle is held steady (more so when it surges and acts stupid). I don't think the spring is broken as it wouldn't work at all, but you might spray it with some wd-40 and on that note, compressed air or carb clean the entire throttle linkage thing, get all that nice and clean (you probably already did, but why not...)

How's the spark plug? Why not replace it or at least make sure it's gapped to .030 (this really shouldn't make a difference, but eliminate one more possibility).

The air filter, too, and the pre-cleaner, then again if you ran it with this off at any stage and it acted stupid, that wouldn't be it.

Yeah, replace the fuel if it sat with it, and while you drain it, pull the carb bowl off and check the float isn't stuck. On the notes of oil, I've been running 10w-30 synthetic blends, I never understood the recommendations but that is not the problem :laugh:

btw, my '05 surges until I engage the blades, then it settles down...
This annoys me, but I just tolerate it.

Sooner or later you'll get it, it's something stupid but the engine's fine, good luck.

05-01-2007, 11:22 AM
Ok...here's the pic's of the engine housing...topsite, my info told me to gap the plug at .040...so I did...same as the old plug... Anyway, t's running fine now...not sure how crucial that gap is..anyway...again,...thanks to all for your help and promptness...wish I could buy you all a REAL beer...:drinkup:

05-02-2007, 04:26 AM
in summer 10w-30 and sae 30 are the same. they both are cert. for high temps.. one is for low temps too.

personally i use 0w-30 in my cv14t ....