Mower starts, but won't stay running

wolfsmane

Full Member
Joined
Dec 7, 2006
Messages
52
Likes
1
Points
8
#1
Husqvrana YTH20K46 with the Kohler Courage 20HP.

This mower will crank with choke engaged, but die 5 seconds later as if I turned the key off. It doesn't matter if I leave the choke on, or try to take it off choke. The only difference is if I take it from being choked, and move it to the slowest running speed, it will take about 10 seconds to die instead of 5 seconds. It will not start without it being choked.

List of things I have done to try and remedy the problem:
Thought it was junk in the gas/carb, so I dropped the gas tank and thoroughly cleaned, and replaced all fuel line and installed a new filter.
Pulled the carb and cleaned it several times, thinking I must have missed something. Ended up buying a brand new carb out of frustration. Used new gaskets.
Replaced ignition module/wire and new spark plug.
Replaced the starter solenoid.
Adjusted the valves .005 for the intake and .007 for the exhaust.
Repaired the positive wire that goes to the fuel cutoff solenoid, because it had a melted spot in the insulation from laying on the block.
Started using NON ethanol gas in it. Was using ethanol before cleaning the fuel system. Because I didn't realize how bad ethanol is to these engines.

I looked the best I could for frayed wiring, thinking maybe something is shorting out. Hard for me to do since I have several herniated discs.

I tried running the mower after doing each one of these repairs, to check if it was fixed. NONE had any affect on how it ran.

Out of frustration, I got a small spray bottle filled with gas, and after starting the mower, sprayed gas straight into the carb, and it ran perfect for as long as I sprayed. It died as soon as I stop spraying.

Small mower bonfire is scheduled for nest weekend, lol
 

billr

wrench
Staff member
Joined
Mar 12, 2007
Messages
6,174
Likes
70
Points
48
#2
Small mower bonfire? A 20 hp mower seems kind of big to me!

Want to try something unusual? Take the carb off, but still connected to the fuel system and blow through it with a leaf-blower or such; see if a fuel mixture comes through or just air. I assume this is a gravity feed system, no fuel pump; is that correct?

PS: I have been using E10 for many years and in many kinds of engines with no problems. Don't waste too much time hunting for that snipe.
 
Last edited:

grcauto

Hero Member
Joined
May 29, 2014
Messages
298
Likes
19
Points
18
#3
Husqvrana YTH20K46 with the Kohler Courage 20HP.

This mower will crank with choke engaged, but die 5 seconds later as if I turned the key off. It doesn't matter if I leave the choke on, or try to take it off choke. The only difference is if I take it from being choked, and move it to the slowest running speed, it will take about 10 seconds to die instead of 5 seconds. It will not start without it being choked.

List of things I have done to try and remedy the problem:
Thought it was junk in the gas/carb, so I dropped the gas tank and thoroughly cleaned, and replaced all fuel line and installed a new filter.
Pulled the carb and cleaned it several times, thinking I must have missed something. Ended up buying a brand new carb out of frustration. Used new gaskets.
Replaced ignition module/wire and new spark plug.
Replaced the starter solenoid.
Adjusted the valves .005 for the intake and .007 for the exhaust.
Repaired the positive wire that goes to the fuel cutoff solenoid, because it had a melted spot in the insulation from laying on the block.
Started using NON ethanol gas in it. Was using ethanol before cleaning the fuel system. Because I didn't realize how bad ethanol is to these engines.

I looked the best I could for frayed wiring, thinking maybe something is shorting out. Hard for me to do since I have several herniated discs.

I tried running the mower after doing each one of these repairs, to check if it was fixed. NONE had any affect on how it ran.

Out of frustration, I got a small spray bottle filled with gas, and after starting the mower, sprayed gas straight into the carb, and it ran perfect for as long as I sprayed. It died as soon as I stop spraying.

Small mower bonfire is scheduled for nest weekend, lol
Make sure the tank is venting. May want to try that first. Remove or loosen the gas cap and see if it runs. If it does the vent is clogged. Make sure the float is set correctly? You need to make sure the jet not being blocked by anything. A little piece of lint will mess them up. I blow them out with my air gun at 175 psi. Also the cutoff solenoid needs to be completely clean on the working end. Make sure it's opening.
 

wolfsmane

Full Member
Joined
Dec 7, 2006
Messages
52
Likes
1
Points
8
#4
Small mower bonfire? A 20 hp mower seems kind of big to me!

Want to try something unusual? Take the carb off, but still connected to the fuel system and blow through it with a leaf-blower or such; see if a fuel mixture comes through or just air. I assume this is a gravity feed system, no fuel pump; is that correct?

PS: I have been using E10 for many years and in many kinds of engines with no problems. Don't waste too much time hunting for that snipe.
You are correct, no fuel pump on this model.
 

wolfsmane

Full Member
Joined
Dec 7, 2006
Messages
52
Likes
1
Points
8
#5
Make sure the tank is venting. May want to try that first. Remove or loosen the gas cap and see if it runs. If it does the vent is clogged. Make sure the float is set correctly? You need to make sure the jet not being blocked by anything. A little piece of lint will mess them up. I blow them out with my air gun at 175 psi. Also the cutoff solenoid needs to be completely clean on the working end. Make sure it's opening.
I will definitely try to gas cap, thanks.
Just weird that it can get enough gas to start but not continue to run.

As far as the jet, I "thought" I cleaned it as well as it could be cleaned, with no improvement. Then, I bought and installed a brand new carb, with no change in it running, so I would assume that rules out a clogged carb.

I am not sure if the float can be set on these, correct me if I am wrong. It is an all plastic float.

Fuel cutoff solenoid - I forgot to state that I did replace that on the OEM carb, with no improvement. In fact, after installing the new solenoid and finding it didn't have any effect on how it ran, I took the old solenoid and cut the entire tip off so it could not stop the flow of gas. Again, no change in how it ran. Then, the new carb I bought had a new solenoid with it, and again, no change whatsoever.

Out of everything I have done, NOTHING has made any change or improvement in how it ran.
 

grcauto

Hero Member
Joined
May 29, 2014
Messages
298
Likes
19
Points
18
#6
Try the gas cap. It's a shot. Seen it on a few over many years but it's usually not a problem until the engine runs for a minute or two. I do remember a couple that starved them fairly quick. Maybe that is one of them.
 

wolfsmane

Full Member
Joined
Dec 7, 2006
Messages
52
Likes
1
Points
8
#9
Left the cap off. I tried cranking it several times. No change. Cranks under choke only, runs for about 2-3 seconds, then dies. Doesn't matter if I adjust idle lever after cranking. If I adjust idle lever to the slowest setting after cranking, it runs about 5 seconds before dying.
 

billr

wrench
Staff member
Joined
Mar 12, 2007
Messages
6,174
Likes
70
Points
48
#10
Do the "sanity check", try running it again by spritzing gasoline into the carb. If it will keep running, even if very poorly, then we can focus on this being *just* a fueling problem. No fuel pump and the safety-solenoid has been neutered, correct? Really, try blowing through the carb and see if any fuel comes out. Is the float bowl filled at all when you take the carb off, does any fuel trickle out if you turn it upside-down?
 

wolfsmane

Full Member
Joined
Dec 7, 2006
Messages
52
Likes
1
Points
8
#11
No fuel pump on this model.
Not positive what the safety solenoid is.
The float bowl pours gas out when I take it off. Did this on the original carb as well as the new carb.
I will try the blowing air through and spritzing gas into the carb.
 

billr

wrench
Staff member
Joined
Mar 12, 2007
Messages
6,174
Likes
70
Points
48
#12
"Fuel cutoff solenoid - I forgot to state that I did replace that on the OEM carb, with no improvement. In fact, ...

That solenoid, the one you mentioned in reply #5
 

billr

wrench
Staff member
Joined
Mar 12, 2007
Messages
6,174
Likes
70
Points
48
#14
"Out of frustration, I got a small spray bottle filled with gas, and after starting the mower, sprayed gas straight into the carb, and it ran perfect for as long as I sprayed. It died as soon as I stop spraying."

Did you miss this at the start of the thread? It pulls in enough air to run, as long as it gets fuel. However, I did suggest that the OP run that test again, just to be sure...
 

grcauto

Hero Member
Joined
May 29, 2014
Messages
298
Likes
19
Points
18
#15
Brain fart....That carb needs to be blown out and make sure the filler valve and float are right. There's just not that much to these. I've had new carbs right out of the factory box and bag needing to be blown out to work.