# Kohler engine problesm



## harryschopshop (Apr 22, 2012)

Hi, I'm new to the forum and need some help. I am a mechanic and have been working on gasoline, diesel and gas turbine engines for 25 years, but this one has me stumped.

I have a 1997 JD Sabre 2554HV with 400 hours on the Kohler CV25-69525 engine. It has the 24 853 81-S carb (with accelerator pump). The engine ran fine last year, but this year is a different story. 

At first it wouldn't idle unless the choke was pulled and then only up to 1/3 throttle with the choke pulled. I cleaned the carb and installed the accelerator pump kit (p/n 24 757 21-S). 

At that point it would run from idle to WOT as long as the choke pulled all the way out. As soon as I engaged the deck, it would die. 

I pulled it apart again and installed the overhaul kit (p/n 24 757 18-S). Now it will idle and run to 1/2 throttle without the choke pulled but will not run WOT unless the choke is pulled. I can engage the deck and it pulls the engine down a bit but it will not recover to WOT.

I cannot afford a new carb at this point, but it's looking like that is next. Does anyone have any thoughts on this?


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## Mickey (Aug 14, 2010)

Just making an assumption here. Have you checked fuel line between tank and carb? Also have you checked fuel pump and tank vent? Need to find source of fuel restriction/starvation.


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## jhngardner367 (Apr 5, 2011)

Welcome to the forum! I would agree with Mickey. You may also make sure the fuel is fresh. These engines are lower compression than most vehicles,usually(depending on mfgr),but stale fuel can affect any of them.


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## Kohuth77x (Mar 16, 2012)

Drain all fuel from everything and just clean your carb real well again with carb and choke cleaner and make sure all the old fuel is out and put in all new gas with 1/3 of a bottle of HEET or other water remover additive and it should run mint again


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## harryschopshop (Apr 22, 2012)

Thanks guys,. I should have mentioned that the tank is clean, the filter is new, the gas is fresh and fuel pressure is good. I will check the vent in the cap as i had not thought of that. I'll let you know.


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## harryschopshop (Apr 22, 2012)

Ok, sorry for the long wait to update. The carb is clean, the vent in the cap is clear. The only thing I can think of at the moment is not enough fuel pressure. I have to find out what it is supposed to be and check it. WIll keep ya'll posted.


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## jhngardner367 (Apr 5, 2011)

Fuel pressure should be 1.5- 4.3 psi.


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## Country Boy (Mar 18, 2010)

If you have exhausted the carburetor angle, have you looked into the ignition system at all? Kohler used the Smart Spark system on some of those Command engines and it can give odd problems when it acts up. Yours may or may not have it. They can be sensitive to voltage changes in the system and to dirty contacts on at the connections. The Smart Spark box controls the spark advance and timing of the engine rather than the coils themselves. Also, have you checked to be sure you have a strong spark on both cylinders? My friend's father in law had low power, slow running, and a bit of a stumble from his 25hp Kohler Command and it ended up being a bad ignition coil on the #2 cylinder. It was sparking, but it was a weak, somewhat intermittent spark. We swapped in two new coils (it was a real PITA to get the engine out to work on it) and it now runs like a dream with over 2200 hours on it. It may end up being carburetion or fuel related, but it never hurts to check the unit over. I'd also do a quick leakdown test on both cylinders.


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## harryschopshop (Apr 22, 2012)

My apologies guys, but it's crazy enough to write a country song around here...anywho, I checked the fuel pressure, vacuum and the ignition system. I used a timing light to check the plugs for fire. I had a good spark at idle on both plugs, but when i tried to go WOT with no choke, it was the same result. I don't know if i can upload video, but i have about 2 psi of fuel pressure at idle (choke/no choke) and the vacuum/pressure at the fuel pump is between 1 psi and .5 vacuum at idle. Seems to be on the low side but not sure for the vacuum/pressure. I'll do some more tests today, weather permitting.


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## Mickey (Aug 14, 2010)

If it is running at idle but dies when throttle is opened, I suspect fuel blockage internally to the carb. Would require disassembling the carb and soaking in carb cleaner to free up passages. When disassembled one can also physically look for something amiss internally.


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## dangeroustoys56 (Jul 26, 2010)

It almost sounds like theres a leak /blockage in the vacuum line to the pump - ive replaced the vacuum lines before on some of my twins- ive seen a cub cadet with a v twin briggs plug the vacuum line from the valve cover with built up crud ( that was metal) .


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## Bill Kapaun (May 8, 2007)

Did you physically clean the carb jets?


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## harryschopshop (Apr 22, 2012)

yes, i took the carb apart completely and cleaned it out. I'm going to get a fuel pump this weekend...the vacuum/pressure needed to run the engine was there but was a bit on the weak side i think...fuel lines/vacuum lines are new as are the clamps...


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## 1961cuboriginal (Sep 7, 2014)

Check the valves


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## jhngardner367 (Apr 5, 2011)

Also, check the crankcase breather .


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