Really would like to mow some grass:

[JOHNNYCHRISTIAN]

I have a JD LX 178, I should say my wife has a JD LX 178. She likes it so I try to keep it in decent/good running condition for her. Here's the problem, starts right up,
mows for 10 to 60+ minutes & then shuts off like it is out of gas, but it isn't. I have already spent $1000. on it, last time with a JD dealer for $865.00, got it home, same results.
I'm not going to another shop, if I can, I'm fixing it myself. New fuel pump put on at JD, $165.00, I installed new gas line & gas filter, not the cap. Allow it to cool down, starts right up
again & mows again for a short period of time. something is either getting hot & shutting down or maybe a vacuum causing the same

Hope someone can suggest an answer.

 

[workinonit]

Kawasaki?

 

[4570Man]

Bad coil. You could verify the guess by spark testing it after it dies.

 

[workinonit]

That's what I was going to suggest but when mine went bad it did run on one cylinder.

 

[IndyJay]

Did you blow back from fuel filter into tank?
You said you replaced the fuel pump.
Did you check the fuel solenoid on bottom of float bowl?

You can get after market a lot cheaper than OEM and the ones I bought look identical, possibly same manufacturer that supplies JD.

 

[lman]

Make sure the fuel cap is venting.

 

[oldnslo]

When it stops pull the spark plugs and ground them to head to see if you have spark. If no spark then you need to start checking electrical components. 1st would be replace the plugs. Not common but they can go bad and fail when warm.

If good spark check compression or check while checking spark.

If you have both spark and compression all that is left is fuel.

I had one were the carb inlet needle would stick when warm. Replaced the needle and ran fine.

 

[Fuddyduddy1952]

I had a leaf in my gas tank. It randomly shut off.
It's a 2 cylinder Kawasaki. My mowers have clear gas filters so I can instantly see if fuel stops flowing. As it's dying have her choke it, see if it picks up some.
These in line spark testers are $5 Harbor Freight. Put it in one cylinder, it flashes with spark. Run it...see if it's flashing or not as it dies.

 

[Hughman]

Clogged fuel cap vent.

 

[MossRoad]

I have a JD LX 178, I should say my wife has a JD LX 178. She likes it so I try to keep it in decent/good running condition for her. Here's the problem, starts right up,
mows for 10 to 60+ minutes & then shuts off like it is out of gas, but it isn't. I have already spent $1000. on it, last time with a JD dealer for $865.00, got it home, same results.
I'm not going to another shop, if I can, I'm fixing it myself. New fuel pump put on at JD, $165.00, I installed new gas line & gas filter, not the cap. Allow it to cool down, starts right up
again & mows again for a short period of time. something is either getting hot & shutting down or maybe a vacuum causing the same

Hope someone can suggest an answer.

- After is dies, have you tried cracking the fuel cap open and seeing if you hear a hiss? Could be the cap isn't venting (as others have suggested).

Try opening the fuel cap and seeing if you can then start it.

- It could be vapor lock in the fuel line. That's where the fuel heats up so much it changes from a liquid to a gas. It won't resolve until it cools down. If that's the case, you could relocate the fuel line or insulate it.

Vapor lock - Wikipedia

en.wikipedia.org

- Do you have a clear in-line fuel filter? If not, install one. They are cheap. When it dies, look in the filter for the presence of fuel.

- It could be a bad coil that opens up when it gets hot. Do as others have suggested and check for a spark right after it dies.

And welcome to TBN!