K301 Woes

[hunterguy92 17]

Well as normal, fix one problem and find another. My C-120 with 12hp K-301 has been running very smoothly. I rebuilt and tuned the carb a few months back. Yesterday I made a trip from the garage to the backyard (2 minutes) and got off the tractor and let it idle at mid-throttle. After about 30 seconds all of a sudden it started sputtering out, puffing black and I struggled to keep it running. Finally it died and would not restart.

 

I took the air filter off and it was wet with fuel. Trying to start it again, it would sputter and spit fuel out of the carb but not stay running. So naturally I took the carb off (it was clean) and gave it another good cleaning anyway. Float is good when shaking it. Reassembled and put back on the tractor but it still isn’t running right. It will start up after leaving it sit for a while (but rough) and after only running for a few minutes it will sputter, die and not restart. 

 

I checked right after it died and and there was spark. Took the fuel line off the carb and it seems to be pumping fine.

What do you guys think? Points and condenser? Coil? Stuck valves?

 

i really don’t think it’s the carb unless I somehow installed the needle or seat wrong. Super strange that it has been running like a top, starting on second crank and all of a sudden struggles and won’t start.

 

I’m pretty stumped here, so I thank you for your help!

 

Edited June 8, 2018 by hunterguy92

[Goldnboy 910]

I would do a process of elimination.

Check for "good" spark with a tester

Check fuel  , pull hose off pump and see if flowing when cranking starter.

After that it should start unless you have electrical gremlins somewhere.

[pacer 3,169]

Almost certainly your needle/seat has failed -- I've had this almost identical situation and it is always the needle. Even a couple times with a 'new' needle seat. Go ahead and get a new one and you'll be good to go -- or better yet for the cost of a "kit" you can probably get a new carb, one of the imports that are running under $15. Thought be advised to watch the choke set-up, most of them are bassackwards, I switch my old choke shaft/butterfly over to the new.

[hunterguy92 17]

3 minutes ago, pacer said:

Almost certainly your needle/seat has failed -- I've had this almost identical situation and it is always the needle. Even a couple times with a 'new' needle seat. Go ahead and get a new one and you'll be good to go -- or better yet for the cost of a "kit" you can probably get a new carb, one of the imports that are running under $15. Thought be advised to watch the choke set-up, most of them are bassackwards, I switch my old choke shaft/butterfly over to the new.

I actually did change the needle and seat last night when I took the carb apart. Tractor still had the same symptoms.. 

Edited June 8, 2018 by hunterguy92

[pfrederi 17,729]

Did you make sure you set the float to 11/64"  and the drop at 1-1/32" ??  It sounds obvious you are getting excessive fuel it has to get into the engine via the carb so something is amiss there.  Also make sure the splash gasket isn't fouling the float....

Edited June 8, 2018 by pfrederi

[gwest_ca-(File Mod) 11,040]

Check the oil level to make sure the fuel pump is not leaking into the crankcase.

 

Garry

[953 nut 55,191]

Have you been using gas with ethanol in it? Ethanol is hard on fuel system components in small engines, check out this site to find a station that sells real gas.        

http://www.buyrealgas.com/Michigan.html

[JoeM 7,873]

Make sure the float will float. I have a clean coffee can that I pore gas in and check to see how the floats react.

 

[hunterguy92 17]

7 hours ago, pfrederi said:

Did you make sure you set the float to 11/64"  and the drop at 1-1/32" ??  It sounds obvious you are getting excessive fuel it has to get into the engine via the carb so something is amiss there.  Also make sure the splash gasket isn't fouling the float....

I foolishly did not set the float.. Maybe this is adding an additional layer of problems. So the float should have 11/64” when up, and 1 1/32” when down?

I’ll take her back apart and let you know what happens!

[pfrederi 17,729]

13 hours ago, hunterguy92 said:

I foolishly did not set the float.. Maybe this is adding an additional layer of problems. So the float should have 11/64” when up, and 1 1/32” when down?

I’ll take her back apart and let you know what happens!

 

[hunterguy92 17]

3 hours ago, pfrederi said:

 

This did the trick. Can’t thank you enough for aiding me in my troubleshooting!

 

The float must have been off since I bought it and only got worse when I replaced the needle and seat the other day. Over the past few months I’ve constantly been tweaking the carb and it was much stinkier before. Running very smoothly now and I’ll probably use much less fuel!

 

Thanks again!