Kohler CH740S Engine Stalls and Wont Start

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swiederin

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• Jul 10, 2019 / Kohler CH740S Engine Stalls and Wont Start

• #1

My Kohler engine CH740S started stalling out after a couple of hours of mowing. It first started sputtering then it eventually got worse to the point where it died and would have to restart. Progressively got worse.
Changed the fuel filter. Checked the spark plugs. Changed the fuel pump. Now it wont start at all. Oil level is perfect. Air cleaner is good. HAve used several gallons of fuel during this time so fuel shouldn't be an issue.
What should I look for next?

 

Scrubcadet10

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• Jul 10, 2019 / Kohler CH740S Engine Stalls and Wont Start

• #2

So by not starting, it spins over but won't fire, correct?

Take out the spark plug(s) and leave the plug wire connected to it.
Touch the end of the plug to any metal on the engine (away from plug hole)
and have someone turn the key and look for spark between the plug and electrode.

If you have good spark it might be a valve issue... Might.

 

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swiederin

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• Jul 10, 2019 / Kohler CH740S Engine Stalls and Wont Start

• #3

swiederin said:

My Kohler engine CH740S started stalling out after a couple of hours of mowing. It first started sputtering then it eventually got worse to the point where it died and would have to restart. Progressively got worse.
Changed the fuel filter. Checked the spark plugs. Changed the fuel pump. Now it wont start at all. Oil level is perfect. Air cleaner is good. HAve used several gallons of fuel during this time so fuel shouldn't be an issue.
What should I look for next?

Click to expand...

It does crank/turn over. I tested the spark and yes , there is alot of spark. Weird think about this problem is that it was progressive. I mean it started by sputtering after an hour then the next time we started mowing, it started sputtering sooner and so on until most recently it began sputtering right away until now it won't start.

 

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bertsmobile1

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• Jul 10, 2019 / Kohler CH740S Engine Stalls and Wont Start

• #4

Toss a little fuel down the plug holes & see if it starts
If yes then the ignition timing is OK

Do the same down the carb throat
Starts & runs out the fuel = valves are OK

Fuel supply is then the problem
Remove the solenoid from the carb and check that it retracts when the ignition is turned on.
IF it has only 1 wire, it will need to be grounded.

Put a container under the carb & crank the engine
Fuel flows then pump is OK
Hold the float up and crank the engine again
No fuel flow = float is good

You are now left with a dirty carb, loose carb, malfunctioning choke.

 

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geelee

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• Jul 10, 2019 / Kohler CH740S Engine Stalls and Wont Start

• #5

check fuel flow out of tank, sounds like a restriction.

 

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swiederin

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• Jul 10, 2019 / Kohler CH740S Engine Stalls and Wont Start

• #6

geelee said:

check fuel flow out of tank, sounds like a restriction.

Click to expand...

Well after pulling the fuel line from the tank fitting, placing it in a fuel can and cranking it.....it started and ran great for a an hour.....then it was up to its old tricks. I believe there may be something in the tank clogging the fuel pickup.

Thoughts?

 

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bertsmobile1

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• Jul 10, 2019 / Kohler CH740S Engine Stalls and Wont Start

• #7

Yep,
Fairly common problem
Drain the tank, let it dry out then blow backwards up the fuel line with compressed air.
Usually a plugged fuel tanl makes the engine surge for an extended period before it starves the engine.