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18 hp kohler acting up


WML13's Avatar
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05-11-14, 06:25 AM   #1  
18 hp kohler acting up

I have a 1989 Toro Mower powered by an 18 hp kohler twin cylinder Engine. I did a valve job on it 4 years ago, and put in a new Ignition module and fuel pump at that time. The mower has developed the annoying habit of shutting down after about 15 minutes of operation. Let it cool off and it starts again, 15 minutes and it shuts down, starting the process all over. Im thinking that I got a defective module or fuel pump, but thought I would check in with the group to see what the next move is to determine the problem,

 
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05-11-14, 07:02 AM   #2  
A pretty common procedure is at the time of shutdown check for spark first with everything together.

If no spark, disconnect the module from the rest of the wiring harness to isolate the module from the safety switches/ignition witches, etc. If still no spark, replace the module. If you have spark = look at other parts of the electrical.

If you have spark with everything hooked up look at fuel - fuel cap/ carb/restrictions in fuel delivery, etc.

 
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05-16-14, 12:29 PM   #3  
marbobj - check your fuel tank for possible floating obstruction to fuel line

I'm having a similar problem with a 12 hp Kohler Cub Cadet with approx. 500 hrs. I was pretty sure I found some kind of floater or debris in the fuel tank because when I disconnected the fuel line from the fuel filter, no gas until I forced air through the line.
I siphon drained the tank completely and it actually helped for a while but now after running an hour it dies on me and now I can't keep it running by disengaging PTO and playing with choke. And after waiting overnight, it starts right up the next day. I haven't yet replaced the fuel pump but that's where I'm headed next.
Just search the forum for 'Cub Cadet' you'll see my earlier threads and replies I got.
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05-17-14, 02:50 PM   #4  
Yep. Junk in the tank and especially bits of rust on the older models. On yours maybe the gas cap vent plugged. Or the diaphragm in the fuel pump has gotten stiff or cracked with age. That usually doesn't come around with an overnite rest, though. Garbage in the tank would.

Before you replace the fuel pump, I think I would clean it up and get a good gravity flow of gas to the fuel pump. Then see where you are. If it still comes down to the pump and yours is crankcase pulse driven you might check the pulse port

 
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06-11-14, 07:35 AM   #5  
Follow-up to Marbobj on reply to thread I missed last month...

Marbobj,

Sorry I missed your reply on my Cub Cadet 2135 apparent fuel-starvation issue last month, but I had a follow up question.

How do you check the Pulse Port you mentioned when I mentioned about replacing the fuel pump as my next step?
I haven't replaced the fuel pump yet and have been limping by mowing the hour or so, I get before it heats up and dies.
I'll them change to push mowing or weedwhacking for the remainder of evening.

I did take the right cover panel off last night to see if that helped dissipate the heat buildup in the engine compartment. And, it appeared to help since I was able to mow about 2 hours rather than the typical one hour.

I also noticed that where the fuel line is routed back to the fuel tank that it crosses the rear of the engine compartment along the back of the firewall and then is run through a steel-channel of the frame back to the tank.
That frame area seemed fairly hot compared to the other side frame-rail and probably is catchng a lot of the heat from the front exhaust pipe on that side.
I may try removing both sides and see how that affects the run time.
Thanks for your help,
greynold99

 
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06-11-14, 09:05 AM   #6  
The pulse port is a little port, usually at the mounting of the fuel pump to the casing, although it can be more remote with a pulse tube leading to it.

Check to make sure the port is clear and the gasket between the casing and fuel pump has the hole in it matching the fuel pump and casing so as to allow the pulse from the crankcase through to the pump diaphragm.

When you spin the engine over you should be able to feel the pressure from the port.

 
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06-12-14, 10:53 AM   #7  
Reply to Marbobj

Marbobj,
I got your update and will check out when I do my mid-season maintenance this weekend or next - depending on the weather and how fast the grass grows in the meantime. Lots of rain this year...

I picked up a OEM Cub fuel pump from Repair Clinic.com when they had a sale back in Feb or Mar - just haven't installed it yet.
Anyway, there's a dog-leg lever piece that comes out the engine-side connection of the fuel pump and appears to just cycle up & down by about 1/4" to 3/8" - probably driven by one of the cam shaft lobes - Would that possibly create the pulse-port action you describe?
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06-12-14, 03:25 PM   #8  
No, that's a mechanically driven fuel pump. That pump is as you suspect - it's driven off a cam lobe. Forget about the pulse port on that engine.

When you install it put a dab of grease on the arm, then hold the pump in against the cam lobe and turn the engine over slightly. As the cam rotates the pressure will come off the pump drive arm and you can align it a lot easier.

 
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06-13-14, 07:03 AM   #9  
Kohler Fuel Pump

I don't know if I passed on the result of my success with fixing the problem with an intermittent shut down with this engine. I bought a replacement fuel pump and after installing it, I took the old one apart. It was full of engine oil. both front and back of the diaphragm. I was told that this could be caused by overfilling the oil sump, and or lots of climbing steep hills. (lots of hills) With the new pump in place, a replacement module, new fuel line (very soft spot next to the fuel tank connection) and fuel filter, the engine has been trouble free. I still am not really sure which one was ACTUALLY shutting things down at precisely the the time I got out of the garage and started to mow (maybe 5 minutes of running time) but the smoking gun was the oil in the fuel pump.

 
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06-13-14, 08:49 AM   #10  
It sounds like you probably had a bad diaphragm in the fuel pump. Whatever it was it's always good to have it running good again.

Take care.

 
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06-13-14, 11:19 AM   #11  
To WML13 & Marbobj

WML13, glad to hear your issue was fixed with replacing the fuel pump and that looks like my next weekend project. Hill mowing is a good third of my mowing, so may have contributed to my Cub problems.

Marbobj, thanks for the tips and advice on the fuel pump installation - that was definitely not in the 'little' instruction sheet I got.

Later guys,
greynold99

 
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