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Kohler PS-KT725-3012 just dies

#1

W

Wizbang

Kohler in a Troy bilt mustang pivot 17ARCBDT101. The problem started this season. So, I’ve replaced the battery and solenoid, checked the stator and rectifier, cleaned the fuel tank, tank pick up and hoses, replaced fuel pump, replaced the fuel filter, rebuilt the carb, replaced the gaskets, tested the anti-diesel solenoid and ended up removing it and putting in another blank carb plug and checked wiring harness for any damage. It will start and run either in the seat or off the seat with brake set and pto off. I can let it sit and run or start cutting grass. Either way, within about 3-5 minutes it shuts down. I can restart with effort but it still shuts down. No back firing or anything unusual when it’s running or dies. Spark plugs look normal too. Help?


#2

I

ILENGINE

What happens if you loosen the fuel cap. Be away the fuel cap isn't vented, but if loosening the cap fixes the issue that would point to a clogged vapor recovery system. Also something else to check is when it quits do the spark plugs still have spark.


#3

W

Wizbang

Removing the tank cap has no effect. A timing light on either plug wire shows firing up to the engine quitting. I did disconnect the oil sentry with the same results. It will restart and die immediately. I guess I’ll replace the fuel lines and then replace the carburetor. I hate throwing money at the machine.


#4

V

VegetiveSteam

Do you have a way to safely gravity feed fuel directly to the carb from another source? Maybe another small fuel tank or bottle? Obviously am looking to see if the issue goes away when the carb is fed from an alternative source. If the problem is still there you can forget the fuel lines being the issue. If the problem goes away you can forget about replacing the carb. Now you can look at the fuel lines or anything else that might affect fuel delivery. There is an issue that was very common with this engine but it's something that normally happens from day one and not something that develops over time but I wouldn't rule anything out. The issue from brand new was the oil drain back holes in the head were too small and oil couldn't drain back properly into the crankcase. Those drain back holes also let pulses from the crankcase work the fuel pump. When the oil blocks those holes the fuel pump stops working. If this is the issue you should have had this problem from day one but the symptoms you describe are very similar. The rocker cover would have to come off on the fuel pump side to check those holes. Kohler even has a service bulletin on drilling out the holes that were too small. I believe they suggest a 1/4" drill bit but we found that sometimes wasn't enough so we would suggest a 5/16" bit and that did the trick.


#5

S

slomo

Wizbang said:
Removing the tank cap has no effect.
Click to expand...
A fix possibility yes but not often.
Wizbang said:
A timing light on either plug wire shows firing up to the engine quitting.
Click to expand...
Need to figure out why you are losing spark.
Wizbang said:
I guess I’ll replace the fuel lines and then replace the carburetor. I hate throwing money at the machine.
Click to expand...
Fuel lines yes, carb NO. Unless you are buying a new OEM carb.

Some tips to start on.

1.KEEP and remove OEM carb from engine. Break it down removing all small parts. Boil clean the carb on your stove top with water and those automatic dishwasher balls. Use a candy thermometer to keep water/soap temp at 200F. Boil for 30 minutes. Rinse well in clean water to neutralize after. Blow out with compressed air. Reassemble carb. Flip carb over and blow test carb needle/seat (fuel inlet pipe). Should hold 7psi for 30 minutes.
2.Remove fuel tank. Clean out 100% with compressed air. Install new fuel line, filter and shut off valve if you have room.
3.Clean block and cooling fins YEARLY per your engine manual. Remove top metal engine shroud exposing cooling fins. Neglect this and you will get engine damage.
4.Adjust valves per your engine manual yearly.
5.Decarbon cylinder and valves every 5 years or suggested interval in your engine manual. Neglect this and you will get engine damage.
6.Test ignition coil with old spark plug gaped to 0.250" or 1/4". Check for good blue spark. Check for spark if and when engine dies with inline spark tester.


#6

V

VegetiveSteam

Wizbang said:
Removing the tank cap has no effect. A timing light on either plug wire shows firing up to the engine quitting. I did disconnect the oil sentry with the same results. It will restart and die immediately. I guess I’ll replace the fuel lines and then replace the carburetor. I hate throwing money at the machine.
Click to expand...
After the engine stops running but has not yet stopped spinning is there still spark?


#7

S

slomo

VegetiveSteam said:
Do you have a way to safely gravity feed fuel directly to the carb from another source? Maybe another small fuel tank or bottle? Obviously am looking to see if the issue goes away when the carb is fed from an alternative source. If the problem is still there you can forget the fuel lines being the issue. If the problem goes away you can forget about replacing the carb. Now you can look at the fuel lines or anything else that might affect fuel delivery. There is an issue that was very common with this engine but it's something that normally happens from day one and not something that develops over time but I wouldn't rule anything out. The issue from brand new was the oil drain back holes in the head were too small and oil couldn't drain back properly into the crankcase. Those drain back holes also let pulses from the crankcase work the fuel pump. When the oil blocks those holes the fuel pump stops working. If this is the issue you should have had this problem from day one but the symptoms you describe are very similar. The rocker cover would have to come off on the fuel pump side to check those holes. Kohler even has a service bulletin on drilling out the holes that were too small. I believe they suggest a 1/4" drill bit but we found that sometimes wasn't enough so we would suggest a 5/16" bit and that did the trick.
Click to expand...
Who are you and are you trying to cut in line here?


#8

V

VegetiveSteam

slomo said:
Who are you and are you trying to cut in line here?
Click to expand...
Ummm, what?


#9

B

bertsmobile1

Golden rule for mechanics is to find the problem first then fix it
So he needs to work out what is wrong first
I see way too many tools where attempts to fix something that was not broken had done more damage than the original problem.


#10

V

VegetiveSteam

bertsmobile1 said:
Golden rule for mechanics is to find the problem first then fix it
So he needs to work out what is wrong first
I see way too many tools where attempts to fix something that was not broken had done more damage than the original problem.
Click to expand...
Yep. Have to troubleshoot first.


#11

CubbyCommando

CubbyCommando

I'd take a look at all the safety switches in particular the seat safety switch. Use a multimeter to check voltages to the switches. Also, check for a broken or loose ground. The symptoms appear more electrical in nature to me vs fuel related but I'm no expert.


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