L120 Fuel Problem and Technical Manual

[Glessed]

Mower doesn't continue to run after starting. Lasts for about 20 seconds. Appears that gas flow is restricted. I replaced the two gas lines from the fuel filter to the carburetor and gas appears to be pumping OK when the line is disconnected. The fuel shutoff solenoid clicks when the key is turned on. Also replaced the battery.

The fuel filter does not fill. It appears that there is some kind of restriction somewhere in the fuel flow path. I'm totally confused. Can anyone suggest what to do next?

Also, I just bought a Technical Manual (TM2026) and it is only one step better than the Operators Manual. It cover electrical decently but does a poor job of showing the different subsystems and their components. Can anyone recommend a better Technical Manual or Service Manual that I can buy to aid me in current and future troubleshooting?

 

[jinman]

What you are describing is exactly how my LA145 acted when it had a stuck float needle valve. As soon as all the fuel was used up in the float chamber, the engine would die (about 20 seconds after starting). I could remove the hose on the carb side of the fuel pump and blow into it with 30 psi air. That was enough to unseat the float valve and the mower would run fine after that. I did that routine for several months until I got shamed into fixing it correctly. Finally, I replaced the float needle and it has worked fine since. I think ethanol in gasoline makes the rubber needle valve soft and sticky after awhile.

BTW: It is common to not have the filter completely fill with fuel. Mine is always 2/3 to 3/4 full and it doesn't seem to be a problem.

I also believe your engine is a Kohler, but the carbs on Kohlers and Briggs engines are very similar.

 

[Glessed]

Thanks, I'll investigate the float needle possibility. I have the Briggs engine.

 

[BATTY54]

Check your fuel cap vent the L series were known for plugging up the vent hole in the cap. I fixed three as well as my own one year.

 

[Glessed]

I'm beginning to really like this forum. I will try the ideas tomorrow. I'll let you folks know what happened.

 

[gtunney]

I had a similar problem three years ago on my L118 and it was the vent hole in the gas cap. I check it every time out now.

Check your fuel cap vent the L series were known for plugging up the vent hole in the cap. I fixed three as well as my
own one year.

 

[Glessed]

Thanks for your input.

 

[Glessed]

I fixed the problem.

The nut inside the fuel float assembly that holds the fuel shutoff soleniod (bolt) in place has a small jet in the side of the nut as well as a jet in the middle of the nut. The side jet was an area that could not be reached with the carburator spray tube (spray can). I removed the fuel soleniod and cleaned both of the jets, then reassembled. Worked perfectly. It's amazing how a little dirt or varnish can impact things.

I also noticed that the air vent on the gas tank cap was starting to get clogged. Also noticed that the air intake on the fuel pump was dirty. Cleaned both of these items as well.

Next time (if the symptoms happen again) I will be able to do the job within 30 minutes. I can only imagine what it would cost if the repair shop performed the same task.

Thanks for your ideas and inputs.

 

[stuart]

Any chance you might have a photo or two that indicates where I might locate: "The nut inside the fuel float assembly that holds the fuel shutoff soleniod (bolt) in place has a small jet in the side of the nut as well as a jet in the middle of the nut. The side jet was an area that could not be reached with the carburator spray tube (spray can). I removed the fuel soleniod and cleaned both of the jets, then reassembled."
Thank you very much a picture would help me greatly.

 

[Glessed]

See attached. The fuel shutoff solenoid is located at the front/middle of the mower. There are two wires going to it. The carburator assembly needs to be removed (4 bolts). The bowl can then be removed by taking out two screws. Then you will see the nut I was talking about at the bottom of the bowl that holds the fuel shutoff solenoid. Good luck.

 

[Glessed]

Any chance you might have a photo or two that indicates where I might locate: "The nut inside the fuel float assembly that holds the fuel shutoff soleniod (bolt) in place has a small jet in the side of the nut as well as a jet in the middle of the nut. The side jet was an area that could not be reached with the carburator spray tube (spray can). I removed the fuel soleniod and cleaned both of the jets, then reassembled."
Thank you very much a picture would help me greatly.

Here's the correct picture

 

[jinman]

Glessed, I went through all these steps you are going through and came up with many "reasons" for the problems on my mower, but it turned out to be the lightweight plastic needle valve shown below. This is a KNOWN B&S problem. When I was first posting about this problem, another poster told me about the float problem, but I just didn't pay attention. Only when I ordered a carb rebuild kit did I notice the needle valve in the kit was brass instead of lightweight plastic. Replacing the needle valve took care of the problem permanently.

Like you, I would remove and clean the carb and it would work for a week or two and then quit again about 20 seconds after starting. I'd disassemble the carb and it would all be good again. After doing this three or four times, I figured out it was the float needle valve and started using compressed air (very low pressure) on the carb fuel inlet hose to blow open the needle valve. Finally, this practice became tiresome. I took apart the carb for one last time and replaced the needle valve. END OF PROBLEM!

So please, if you have a lightweight plastic needle valve like in the photo below, replace it with a brass needle valve. I think you'll be amazed at how quickly this problem disappears.

 

[Glessed]

Glessed, I went through all these steps you are going through and came up with many "reasons" for the problems on my mower, but it turned out to be the lightweight plastic needle valve shown below. This is a KNOWN B&S problem. When I was first posting about this problem, another poster told me about the float problem, but I just didn't pay attention. Only when I ordered a carb rebuild kit did I notice the needle valve in the kit was brass instead of lightweight plastic. Replacing the needle valve took care of the problem permanently.

Like you, I would remove and clean the carb and it would work for a week or two and then quit again about 20 seconds after starting. I'd disassemble the carb and it would all be good again. After doing this three or four times, I figured out it was the float needle valve and started using compressed air (very low pressure) on the carb fuel inlet hose to blow open the needle valve. Finally, this practice became tiresome. I took apart the carb for one last time and replaced the needle valve. END OF PROBLEM!

So please, if you have a lightweight plastic needle valve like in the photo below, replace it with a brass needle valve. I think you'll be amazed at how quickly this problem disappears.

It appears that we have discussed this topic very thoroughly. We should all be proud! BTW, I will also replace the needle valve. Thanks for all the inputs including your successes and pictures.

 

[mlebied]

unbelievable! I was mowing the lawn for the last time this season, and halfway through the job, the tractor quit. I could hear it starting to run rough, like it does when the fuel is empty. Looked down and confirmed the tank was almost full. Fiddled around with a few things before determining the engine wasn't getting fuel. The nice design of the JD fuel filters allow me to easier determine fuel flow. After awhile I resorted to the best troubleshooting tool - the internet - and found this post. Surely it couldn't be ~that~ simple. But sure enough, cleaned out the fuel cap vent with a toothpick - and WOW! I saw the fuel start flowing through the filter and it started right up. Still can't believe it was that simple - but glad it was! really did not want to have to take the tractor apart in the cold, windy weather today! Thanks for the tip BATTY54!

 

[BATTY54]

Your very welcome, I picked up that info while I was at a JD dealer, just picking up parts. A guy pulled in with a L118 on a trailer. A service tech went out wth a small piece of wire and cleaned the vent in the fuel cap then sent the customer on his way. He later told me they were doing a few a week when the L series first came out.