20 Most Recent Kohler CH25 PA-CH730-0040 Command Gasoline Engine - Page 9 Questions & Answers

Hi John, I am Kelly and welcome to FixYa.
Check the inside of the gas tank and see if there is a fuel pick up tube. This sounds like you have a floating vs sunken pick up tube inside the gas tank.

The next time it quits on you; pull off the main fuel line at the gas tank and see if there is MAX fuel available. If not the problem is in the tank.
- If you do have MAX fuel flow we have other troubleshooting to do that I will post about later.

I will keep watching this post for any responses because I don't think that is the problem but the gas tank has to be eliminated first.

Kelly

Before you start check the wires on the left side of the air shroud of the engine. That is the rectifier assy and if one of those wires is broken it will not charge.

Here is what the book says.




That is pretty much it without using the Kohler specialty tester for the charging system.

Thanks for using FixYa.

Kelly

First off the readings your stating are a bit low for BOTH cyclinders but the engine has an automatic compresson release so the readings may be low.

Usually we do a leak down test. The service manual calls for using a tester but I have a spark plug fitting made from a drilled out and tapped spark plug that had the ceramic and electrode removed that was replaced by a fitting and air chuck.

The reason you do a leak down test is:

Compression Test
Some of these engines are equipped with an automatic compression release (ACR) mechanism. Because of the ACR mechanism, it is difficult to obtain an accurate compression reading. As an alternative, perform a cylinder leakdown test.

You charge the cylinder head with 50 PSI and listen for leaks from the engine. (you can increase the pressure if necessary.) There is a tester with a gage for this but I have never used it nor do I own one.. so the red, yellow, and green steps below willnot apply.

Leakdown Test Results

Air escaping from crankcase breather ........................................................ Defective rings or worn cylinder.

Air escaping from exhaust system .............................................................. Defective exhaust valve/improper seating.

Air escaping from carburetor ....................................................................... Defective intake valve/improper seating.

(Below N/A without tester)

Gauge reading in “low” (green) zone .......................................................... Piston rings and cylinder in good
condition.

Gauge reading in “moderate” (yellow) zone .............................................. Engine is still usable, but there is some wear present. Customer should start planning for overhaul or replacement.

Gauge reading in “high” (red) zone ............................................................. Rings and/or cylinder have considerable
wear. Engine should be reconditioned or
replaced.

Thanks for using FixYa.

Kelly

The service manual is here:

http://www.kohlerengines.com/onlinecatalog/pdf/tp_2428_b.pdf

It states this for will not start:

Engine Cranks But Will Not Start
1. Empty fuel tank.
2. Fuel shut-off valve closed.
3. Poor fuel, dirt or water in the fuel system.
4. Clogged fuel line.
5. Spark plug lead(s) disconnected.
6. Key switch or kill switch in “off” position.
7. Faulty spark plugs.
8. Faulty ignition module(s).
9. SMART-SPARK™ malfunction (applicable models).
10. Carburetor solenoid malfunction.
***11. Diode in wiring harness failed in open circuit
mode.***
12. Vacuum fuel pump malfunction, or oil in vacuum
hose.
13. Vacuum hose to fuel pump leaking/cracked.
14. Battery connected backwards.
****15. Safety interlock system engaged.****

This points to a problem with either Item 11 or item 15 above.

Start troubleshooting by performing test 1 and 2 on page 132. (this SHOULD isolate the problem)

Ignition module checkout is on page 134.

See page 141 of the service manual for the wiring harness diode. To check it you would read the RED wire off if the switch to the black wire on the flywheel stator. It should only READ in one Direction (reversing the meter leads)

Also disconnect the GREEN wire off of the oil sentry and see if you get spark. If the engine is low on oil or the sensor is bad it will ground the spark. (page 118)

See page 114
Diagnostic Aid #7 “IGNITION SYSTEM” (no spark)
Possible causes:
1. Spark plug
2. Plug wire
3. Coil
4. Coil circuit(s)
“35 Pin” (MA 1.7) Metal-Cased ECU: Circuits 1,
19, 40, 40A, 43, and relay.
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Circuits
22, 23, 65, 66, 30, and relay.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Circuits
30, 31, 65, 66, relay and relay circuit 30.
5. ECU grounds
6. ECU

That is pretty much all of the troubleshooting. I do wish you the best and if you need more assistance just respond here and I will gladly help you.

Thanks for using FixYa,

Kelly

Check that the ACTUAL position of the throttle plate closes off the carb bore. Often the actuating mechanism slips on the shaft on aome motors due to a loose clamp.

Check all your fuel hoses make sure they are not broken or any holes are in the lines themselves. Also clean out the Carb and all the ports leading to the engine with some carb cleaner. If you still have raw fuel leaking then you are going to have to replace the top gasket on the motor where your cylinders are located.

Usual cause is wrong timing OR burned intake valve or sticking intake valve..

If it uses shaft mounted flywheel magneto possibly the key between the shaft an flywheel has been sheared.

check the alternator output straight from the coils usually around 18 volts ac if this is good may be down to the charge regulator / rectifier

The engine is NOT burning clean and the exhaust gases contain unburned fuel which burns in the muffler. This could be a mixture problem or possibly a timing problem or maybe the exhaust valve timing is wrong or a burned valve or seating problem. Do a COMPRESSION test as a first step.

When fuel ran out, dirt in the bottom of the tank either plugged the fuel filter or the carbuerator.

Flush these out try again.

With the choke on, added vacuum helps pull fuel in through obstructions.

hi, please check valveclearence

Contact your local vendor.

The highest probability is replace the voltage regulator.

Have you added or modified anything electrical?

these regulators don't handle very much in the way of regulation and are really only designed to recharge the battery after starting.

Hope this tip helps.

R/
Davdi

Sounds like engine is flodding. Have carb float checked, make sure it is at the correct height

ALWAYS CHECK THE POINTS!!! 20 years operating this engine and you'd think I would know better. The points were severely pitted. Spec said .020 but actual is .013. The cold weather had me suspecting a carb problem. DOH!

yes the carburetor is clogged up and need to be cleaned and possible rebuilt. you may get away with a cleaning. when you have to have the choked closed to allow to run it is a sure sign of dirt in the carb jets.

remove the carb and clean it with carb cleaner and compressed air.

if this is something you do not know how to do i can explain step by step. but i asure you this is the problem. a cleaning may or should only take you less than one hour. let me know if i can walk you through it.

hi

remove both exhaust mufflers and clean them of carbon deposit.pay attention at the screens from there(if they exists).try again start the engine

regards savumihai71