Lawn Care Forum banner
Cancel
Create thread New Forums

Kohler CV624 20HP SURGING Problem

Jump to Latest
1 - 18 of 18 Posts
V

vohtahn

· Banned
Joined
·
6 Posts
Discussion starter · #1 ·
I have a Craftsman rider with a Kohler CV624 Command Pro engine with awful surging and running problems. The engine will not run unless the choke is pulled fully out and then if sitting under no load the engine hunts and surges. If driving the tractor with choke out the engine runs very well. I have just totally soaked, cleaned and rebuilt the carb and replaced the fuel filter and spark plugs. The engine runs better but still has the same problem as before.
The fuel pump seems to be working okay and the spark is good as the engine fires right up every time.

Engaging the drive causes it to run pretty smoothly but as soon as you remove the transmission "load" the surging starts again.

I have looked at everything else including the governor (which seems to be working correctly) and can only guess that either A- the carb is defective and should be replaced, or B- the adjustments are just so incredibly fine on this carb that it is almost impossible to set it correctly!

Anyone have any ideas?
 
#2 ·
You're getting there...
Now replace the air filter, and that rubber pcv or crankcase breather hose.

And I can almost guarantee it ain't a carb problem, at least not one requiring
replacement, however adjusting the screws is a bit hit and miss...
Best to do it one at a time after what has been replaced and cleaned.
 
#3 ·
I have run into that before on a mower, but I can't remember which mower and engine. I think it has something to do with the emissions. Has it always done that or jsut start recently?
 
#4 ·
vohtahn said:
I have just totally soaked, cleaned and rebuilt the carb
Click to expand...
Can you go into detail how you performed this ?

What did you soak the carb in ?
How did you clean after soaking ?
Did you install a rebuild kit ?

The only other things that MAY cause the engine to run properly on full choke only would be leaking intake or carb mount gaskets or a cracked intake manifold, But I haven't seen any of these bad that required FULL choke to run properly.
 
Save
Reply Quote Like Like
Discussion starter · #5 ·
I soaked the carb in gallon can of Gumout Parts Cleaner after removing all removable parts including main jet, then blew all out with compressed air. Installed the Kohler rebuild kit and new gaskets. Don't see any crack in the intake manifold as far as I can see.

Really at a loss here.
 
#6 ·
The main jet, did you poke a small wire or something throught to make sure it goes through all the way and is a nice clean round hole? Way it sounds is that it is not getting enough fuel. Have you adjusted the fuel float at all? If you unscrew the fuel solenoid on the bottom of the bowl is there a nice stream of gas coming out?
 
Discussion starter · #7 ·
Main jet is nice and clean- I looked through it to make sure. Pleanty of gas from fuel bowl- new float installed with carb kit. I didn't poke anything through the jet but soaked it, also sprayed it through with Gumout and blew it out with compressed air. Any other ideas?
 
#8 ·
Sometimes you have to adjust the fuel float, but not all. If it is brand new, it might have to be adjusted, because it is not getting enough fuel if you have it on full choke. Was there a sheet that told you how to adjust the float on the carb?
 
#9 ·
Sounds like your slow jet may be plugged. Was that cleaned? That's the tube that goes from the top of the carb, through the venturi and down into the bottom part of the carb. To remove it, the top cover needs to come off the carb. The cover has three screws. The slow jet is brass and should have a straight blade screw head on it. Be sure the entire length of the tube is clear. It supplies gas to the top side of the carb for the slow (lightly loaded or no load) circuit.
 
#10 ·
Gumout is not CARBORATOR cleaner. It's OK for cleaning oil and grease off an engine, but you need a solvent based CARBORATOR cleaner. Since you can make up for your engine running poorly by adjusting the choke, this is a sign that the fuel air ratio is out of wack, usually caused by a build up of Varnish in the carb. Over time old gasoline turns to Varnish cloging up the insides of your carb, this is why the manufacturer recomends draining the gas and running the engine dry for seasonal storage.

Carb Cleaner will desolve this varnish(I don't believe Gumout will) With the straw on the cleaner can spay liberally through all those little hole, blow out w/ air. put back togeather. turn your adjustment needles in till they just bottom out. Then back out 1.5 turn. Start engine and let it get to operateing temp. Do the idle adjust first, turn it out till the eng. starts to sputter, then back in till it starts to sputter again, then set it half way between. If there is a high speed adjustment needle, do the same for it.

Sounds to me that you are not getting enough fuel for the amount of air that is comming in w/choke open. So when you close the choke down, you are getting less air, thereby a better balance of fuel to air. Do you know what I mean? I'm pretty sure it is a carboration problem.

This time of year, everyone is getting their machine out of the shed that they didn't drain, and for sure the Carb is got Varnish clogging the jets.

Next storage time, empty the gas tank, mix some STABILS w/ a gallon of gas. Put in just enough to start the engine. then run it till it dies. put a teaspoon of oil in the spark plug hole, and turn engine over a few times to coat the cylinder, and your good for storage. Any little bit of gas that is in there will have gas stabilizer in it.

Hope this helps
 
#13 ·
Gunk is a degreaser also. Your problem is probably Varnish, as in Laquer Varnish, Paint. Not grease or oil. you need solvent! As in Carborator Cleaner! You have to spray it through all those little holes and get it clean ed out. Take out the needle valve on the float also and make sure all that stuff is clean.

The adjustments are as I stated before.
 
#14 ·
I have a Kohler 25 hp, I think it's a model number 730 something or other. This is on a Scag Tiger Cub purchased new last year. It has all of 14 hours on it, and it does the exact same surge/hunt under no load. It smoothes out under load or with about half choke. It's done this since day one.

I put the governor spring in the hole farthest from the pivot, and this has greatly reduced the severity. It still hunts but not nearly as bad nor as fast.

(For what it's worth, the manufacturer most certainly does NOT recommend draining the fuel. Drain vs not drain is like a Ford vs Chevy can of worms!)
 
#15 ·
Engine surge comes from dirty jets in the carb or overstretched Governor springs(NOT COMMON). A technician cleans are carb correctly and fixes the surge, a parts changer washes it out and reinstalls with the same problem.
 
Save
Reply Quote Like Like
Discussion starter · #16 ·
When I said GUNK I meant their Carb and Parts Cleaner which comes in a gallon can with a dipping basket- not the standard GUNK Degreaser. I will remove the carb and soak it again just to be absolutely certain all varnish is gone and then I'll report the results.
 
#17 ·
vohtahn,

I was done posting but just can't help myself....

This plastic float is not adjustable, From reading your posting you have ample fuel in the float bowl.

Now, The reason I asked how you cleaned this carb;

EPA cracked down on chemical companies many years ago and made them re-structure their carb cleaners. Anymore they are water or mineral spirits based, They will not properly dissolve lacquered fuel in the float bowl much less inside a plugged/restricted passage/port.

I don't know that you will accomplish any better results by soaking again due to these reasons.

The best thing and process is carb & choke spray cleaner in a aerosol can with the straw taped to the can. Use the method betmr explained, I ditched the soak for the spray cans when it went south....

Do NOT buy Gumout brand spray cleaner either, It's nothing more than mineral spirits in a spray can. Here at home I use SuperTech from Walmart at a buck twenty-nine, If I have to buy a different brand I spray a little on my finger first. If feels cold and is not oily feeling and evaporates quickly that's the type that will cut ANY varnish you spray it on.

Word of caution;

Hold the carb away from your eyes while shooting this cleaner into ports. If you have a plugged one or hit a blind one it can shoot back in your eyes, That my friend WILL make you cuss and cry at the same time.


Good Luck
 
Save
Reply Quote Like Like
1 - 18 of 18 Posts
About this Discussion
17 Replies
9 Participants
Last post:
MAD199
Lawn Care Forum
posts
7.2M
members
230K
Since
1999
A forum community dedicated to lawn care and landscaping professionals and enthusiasts. Come join the discussion about performance, modifications, classifieds, troubleshooting, maintenance, and more!
Full Forum Listing
Explore Our Forums
Lawn Mowing Pesticide & Herbicide Application 🔧 Mechanic and Repair Business Operations Lawn Mowing Equipment