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CH23 bogs down and dies when engaging pto

#1

M

mackmanj1

I have a kohler CH23-76591. When the mower came to me it wasnt running. I cleaned the carb, replaced all fuel lines and fuel pump and got it running. I then found i had spark on one cylinder only. Because it was in a Grasshopper 223 zero turn mower and you have to pull the motor to get the shroud off, i decided to replace both coils and now have good spark on both cylinders. I pulled the carb off again and cleaned it again. Checked the compression on both cylinders (120psi on both). I checked to make sure the fuel solonoid wasnt loosing current during pto engagement and that it wasnt excessive load from mower deck. I found that if I move the choke to half on the pto will engage without the engine dying. Im not sure what to look for now. I forgot to add that i did a complete service with new air filters and spark plugs. i even put another set of spark plugs in to make sure they were good. Thanks in advance for any help.


#2

graydog

graydog

mackmanj1 said:
I have a kohler CH23-76591. When the mower came to me it wasnt running. I cleaned the carb, replaced all fuel lines and fuel pump and got it running. I then found i had spark on one cylinder only. Because it was in a Grasshopper 223 zero turn mower and you have to pull the motor to get the shroud off, i decided to replace both coils and now have good spark on both cylinders. I pulled the carb off again and cleaned it again. Checked the compression on both cylinders (120psi on both). I checked to make sure the fuel solonoid wasnt loosing current during pto engagement and that it wasnt excessive load from mower deck. I found that if I move the choke to half on the pto will engage without the engine dying. Im not sure what to look for now. I forgot to add that i did a complete service with new air filters and spark plugs. i even put another set of spark plugs in to make sure they were good. Thanks in advance for any help.
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P
mackmanj1 said:
I have a kohler CH23-76591. When the mower came to me it wasnt running. I cleaned the carb, replaced all fuel lines and fuel pump and got it running. I then found i had spark on one cylinder only. Because it was in a Grasshopper 223 zero turn mower and you have to pull the motor to get the shroud off, i decided to replace both coils and now have good spark on both cylinders. I pulled the carb off again and cleaned it again. Checked the compression on both cylinders (120psi on both). I checked to make sure the fuel solonoid wasnt loosing current during pto engagement and that it wasnt excessive load from mower deck. I found that if I move the choke to half on the pto will engage without the engine dying. Im not sure what to look for now. I forgot to add that i did a complete service with new air filters and spark plugs. i even put another set of spark plugs in to make sure they were good. Thanks in advance for any help.
Click to expand...
Make sure belt & all the belt pulleys are turning freely.


#3

M

mackmanj1

Belt and all pulleys are free as well as the spindles.


#4

StarTech

StarTech

Try doing a cylinder balance test to see if it is running on cylinders equally without the added choke.


#5

cpurvis

cpurvis

The carburetors on small engines do not have anything like the accelerator pump found on carbureted auto engines. Theh purpose of that pump was to increase the mixture richness when the throttle is opened suddenly.

When you engage the PTO, this places a load on the engine that the governor instantly senses and abruptly opens the throttle to produce the additional power needed to keep the engine from losing RPM. But there is no accelerator pump to enrich the mixture to keep the engine from stumbling and the additional air admitted by the throttle opening causes a lean condition. The is most apparent when the engine is not thoroughly warmed up.

The Cub Cadet shown in my avatar has had this problem since the day it was new. My 'solution' to this problem is to pull the choke out at the same time I engage the PTO, then push it back in when the blades can be heard spinning. Once it's warmed up, I don't have to do this.


#6

B

bertsmobile1

Start by isolating the problem between the mower & the engine.
Reach in and manually move the governor .
At idle you should be able to push the governor arm and make the engine run faster.
If you can not reset the governor.
People regularly set them up backwards because they forget the governor WORK to slow the engine down not speed the engine up.
Do you have manual for this engine ?


#7

ILENGINE

ILENGINE

cpurvis said:
The carburetors on small engines do not have anything like the accelerator pump found on carbureted auto engines. Theh purpose of that pump was to increase the mixture richness when the throttle is opened suddenly.

When you engage the PTO, this places a load on the engine that the governor instantly senses and abruptly opens the throttle to produce the additional power needed to keep the engine from losing RPM. But there is no accelerator pump to enrich the mixture to keep the engine from stumbling and the additional air admitted by the throttle opening causes a lean condition. The is most apparent when the engine is not thoroughly warmed up.

The Cub Cadet shown in my avatar has had this problem since the day it was new. My 'solution' to this problem is to pull the choke out at the same time I engage the PTO, then push it back in when the blades can be heard spinning. Once it's warmed up, I don't have to do this.
Click to expand...
Some of the Command engines do have an accelerator pump. Most do not and I suspect that may be part of his issue. The compression readings on his engine are low ,( below 160 psi) which could be a factor


#8

M

mackmanj1

StarTech said:
Try doing a cylinder balance test to see if it is running on cylinders equally without the added choke.
Click to expand...
Cylinder balance test ok.


#9

M

mackmanj1

bertsmobile1 said:
Start by isolating the problem between the mower & the engine.
Reach in and manually move the governor .
At idle you should be able to push the governor arm and make the engine run faster.
If you can not reset the governor.
People regularly set them up backwards because they forget the governor WORK to slow the engine down not speed the engine up.
Do you have manual for this engine ?
Click to expand...
Yes, downloaded from Kohler. Governor is working properly


#10

M

mackmanj1

Hey Guys.
Thanks for the responses!!! I believe my problem is low compression and age of motor. Im going double check everything today and see what happens.


#11

Hammermechanicman

Hammermechanicman

Curious. Are you engaging pto at idle or full throttle? My Ferris 3100Z manual says to engage at full throttle. I have worked on mowers with big decks that you had to engage at near full throttle or the engine would bog down. My 184 LoBoy will kill the engine unless i have engine warmed up and at near full throttle.


#12

cpurvis

cpurvis

bertsmobile1 said:
People regularly set them up backwards because they forget the governor WORK to slow the engine down not speed the engine up.
Click to expand...
Have to disagree with this statement. Governors work to maintain an rpm, whether than means slowing down or speeding up.


#13

Hammermechanicman

Hammermechanicman

Kinda of a semantics thing. A small engine centrifugal governor does control the engine speed according to load but it does it by acting against spring tension to slow the engine to a balance point. Spring tension speeds it up, govenor works to slow it down. Semantics, it is just a generally misunderstood and misadjusted system. Philosophical $0.02 for the day.


#14

cpurvis

cpurvis

Gotcha.

Bert, please disregard my comment.


#15

M

mackmanj1

Hammermechanicman said:
Curious. Are you engaging pto at idle or full throttle? My Ferris 3100Z manual says to engage at full throttle. I have worked on mowers with big decks that you had to engage at near full throttle or the engine would bog down. My 184 LoBoy will kill the engine unless i have engine warmed up and at near full throttle.
Click to expand...
Deck's engaged at full throttle. The only way to get it to engage and stay running now is to set the choke half on, engage the deck, then push the choke off.


#16

Hammermechanicman

Hammermechanicman

If you have good compression (?) with no leaking head gaskets and good spark on both cylinders are you sure the engine is not running slightly lean? Have you cleaned the carb and checked the main jet?


#17

M

mackmanj1

Hammermechanicman said:
If you have good compression (?) with no leaking head gaskets and good spark on both cylinders are you sure the engine is not running slightly lean? Have you cleaned the carb and checked the main jet?
Click to expand...
I've had the carburetor apart cleaned, wire ran thru every hole possible to run thru, at least 4 times. Soaked in carb dip each time. Did the same with main jet and mixer tube also. New kit installed again on last teardown.


#18

M

mackmanj1

Had something interesting yesterday while putting carburetor back on. While I was installing I broke the ear off the insert where the choke linkage attaches to carburetor. Since I was "down" until parts to repair the choke came in I decided to play with the jetting. Keihein main jets in motorcycle carbs are the same as the one in this carb. I put 2 different bigger size jets in and it made absolutely no change in the way the engine ran. Expecting the bigger jets to cause the engine to load up with fuel and run rich it didnt happen. I took an unmarked jet and drilled it out to 1/16" installed it and it still made no difference. The only way to get the engine to load up with fuel and puff black smoke is to choke it. Im beginning to think I still have a restriction in the high speed circuit. Sounds like a new carb might be needed.


#19

B

bertsmobile1

mackmanj1 said:
Had something interesting yesterday while putting carburetor back on. While I was installing I broke the ear off the insert where the choke linkage attaches to carburetor. Since I was "down" until parts to repair the choke came in I decided to play with the jetting. Keihein main jets in motorcycle carbs are the same as the one in this carb. I put 2 different bigger size jets in and it made absolutely no change in the way the engine ran. Expecting the bigger jets to cause the engine to load up with fuel and run rich it didnt happen. I took an unmarked jet and drilled it out to 1/16" installed it and it still made no difference. The only way to get the engine to load up with fuel and puff black smoke is to choke it. Im beginning to think I still have a restriction in the high speed circuit. Sounds like a new carb might be needed.
Click to expand...
Unless you grabbed the throttle linkage from the governor to open the throttle butterfly then you are just running on the idle jet, not the main jet so changing it will have no effect.
I have ridden a motorcycle for 10 days with no main jet at all ( accidently got tossed away ) and the bike ran fine up to 3/4 throttle because the needle jet is the limiting factor not the main jet.


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