My Tractor Forum banner

1 - 13 of 13 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter #1
Hello Guys, need a little help with a very frustrating issue. I have a 90's STX38 yellow deck. 12.5 Kolher. Since I've owned it, for a couple of years now, it's always been difficult to start. But once started, it runs fine. When it starts I have to be easy on the gas, or it will die. I let it warm up and then I can give it more gas. I've had the carb apart several times, cleaned it, no improvement. Now it won't start at all. It's got good spark, after trying to start it, I remove the plug very little gas on it. I tried ether, it fires up on it then dies, now it won't start on ether. Confused, Thanks.
 

·
Registered
Joined
·
285 Posts
I also found that on a Kohler carb, where the fuel line attaches to the carb,debris had passed thru the fuel filter and clogged up right where the inlet to the carb is,drove me nuts....and I also replaced the fuel pump :eek:(Jim
 

·
Registered
Joined
·
10 Posts
Discussion Starter #5 (Edited)
I have no manual, so I don't if there is a fuel pump.
I checked the carb solenoid, it is working porperly. The fuel
line and nipple entering the carb are clear of any debris.
I've cleaned and cleaned the carb. Maybe there is a small
piece of debris in the slow jet passage, that won't clear out.
Thanks guys, I appreciate all the help.
 

·
Registered
Joined
·
643 Posts
You say you have good spark - your problem is you're not getting fuel.

1. Pull the fuel line off at the carb. Keyswitch on. Do you have good fuel flow? If not, what is blocking the flow? a) Fuel filter, b) fuel shut-off valve, c) fuel pump?
If you cannot determine which, pull the fuel line off at the fuel tank and determine that you have good fuel flow straight from the tank. Follow the fuel line from the fuel tank to the carb and check whereever there is a connection to determine what is obstructing the fuel flow. Remember, the keyswitch has to be on to get fuel through the fuel pump and shut off valve.

2. If you have good fuel flow to the carb, remove the bowl (gently) and check that fuel is flowing through the needle valve, which is controlled by the float. Lift the float up (gently) to see that the needle valve shuts off the fuel. You should have fair flow of fuel through the needle valve.

3) If you have good flow through the needle valve, the float shuts off the flow, and the engine does not start, it's time to pull the carb and clean it. Shove small diameter wires, hat pins, etc., through every orifice you see. Use compressed air to blow through every orifice in sight. Some of these orifices are not easy to see. Look it over thoroughly. Soak it in carb cleaner.

4) The best way IMO to prime an engine for starting is to remove the air filter and spray starting fluid directly into the carb for starting. You can also pour a small amount of gas into the carb if you don't have starting fluid. Putting gas into the spark plug hole is normally not effective way to start an engine.

5) Good luck. Let us know how you make out
 

·
Registered
Joined
·
10 Posts
Discussion Starter #7
Fuel is filling the carb. There is no fuel restriction. Everytime I pull the carb off, an adequate amount of fuel drains out. It has started on ether, but now
even ether doesn't start. When this happens I pull the plug and stick a phillips in the boot, great spark. Continuous spark as I turn the motor over.
I'm stumped. It seems like, little to no gas. I would love to be able to try another carb. Anybody got a extra Walbro? Thanks.
 

·
Registered
Joined
·
643 Posts
Have you removed the air filter and sprayed ether down the carb to see if it would start?? If not, give it a try. If it doesn't start, try putting a small amount of gas down the carb. Let us know if you can at least get it to start!

If you have good fuel flow to the carb, and the carb is full, and the engine won't start, then you are not getting fuel to the engine. Must be the main jet in the carb is plugged.

When you are cleaning the carb, look for any jets that can be removed with a screwdriver or wrench. Take them out and clean any orifices under them. You need to get a wire or hat pin or whatever through all orifices. Also blow them out with compressed air.

Also soak it in carb cleaner for as long as you can. Beyond that, if you can't get it running, you might as well buy a new carb.
 

·
Registered
Joined
·
10 Posts
Discussion Starter #11
Have you removed the air filter and sprayed ether down the carb to see if it would start?? If not, give it a try. If it doesn't start, try putting a small amount of gas down the carb. Let us know if you can at least get it to start!

If you have good fuel flow to the carb, and the carb is full, and the engine won't start, then you are not getting fuel to the engine. Must be the main jet in the carb is plugged.

When you are cleaning the carb, look for any jets that can be removed with a screwdriver or wrench. Take them out and clean any orifices under them. You need to get a wire or hat pin or whatever through all orifices. Also blow them out with compressed air.

Also soak it in carb cleaner for as long as you can. Beyond that, if you can't get it running, you might as well buy a new carb.

I've done all of that, What I can't understand is, once it would run, it would
idle, rev up, run at any rpm range. It would burr like it should, no signs of a
problem. I could mow all day long. What ever the problem is, it goes away.
Then returns the next mow day.
 

·
Registered
Joined
·
72 Posts
http://www.eastcoastpullingparts.com/photogallery/kohler/13carbrebuild.jpg

Check that you have a seal around the top of your float bowl, and that it isn't cracked. I've seen this cause difficult starts on some engines when trying to pushbutton prime.

If you can, remove the main jet body and look for a small hole. Clean that out with a strand from a wire brush. Usually the main jet is inside a post that hangs down the center of the bowl with the float around it.
 
1 - 13 of 13 Posts
Top