John Deere 240 starting issue

[Sherk]

Since I saw another thread on small engines I thought I'd post up my question, somewhat complex.

I have a John Deere 240 lawn tractor with a Kawasaki FC420V-DS00 engine, given to me by a good friend a few years ago. It started and ran great for several years. Then I pushed the clutch in and throttled down without shifting to park to answer a question from my wife. On trying to throttle back up the engine died, and I couldn't get it started for quite some time (I thought maybe I overheated it somehow).

After that session it doesn't want to start. It will, but only if you choke it and get it to fire and as soon as it does, drop throttle to zero (which made me think dirty carb, accelerator circuits plugged, but completely disassembled the carb 3x and cleaned with an ultrasonic cleaner for his, then replaced it with a Chinese carb). Sometimes it will stay running. Then you have to feather (and I mean super slowly) the throttle up to get it to speed, where it has plenty of power to mow.

I've been through everything external. New spark module, adjusted gap, adjusted valves (exhaust was a bit looser than tolerance if I remember right but now both are in the middle of their ranges). New spark plug, fresh gas, new gas filter. New carb still has exactly the same issue, it did not help one bit.

Linkages look like they're working fine? That's something I don't know, maybe the governor isn't working right, but the manual doesn't tell me how to look at that. At my wits end, I want to take it somewhere but I don't have much free cash.

Any thoughts?

 

[The Cobbler]

throttled down without shifting to park to answer a question from my wife. On trying to throttle back up the engine died, and I couldn't get it started for quite some time (I thought maybe I overheated it somehow).

After that session it doesn't want to start.

not very likely the 2 are related . it just happened to be the same time in my wild *** guess .
how's the compression? bad valve(s) or valve guides? intake leak somewhere ? bad fuel pump? , steady good fuel supply to the carb ?

 

[GirlnAgarage]

Probably look at fuel supply next - lines, pump, etc. It's easy for them to get old and fall apart and block the fuel.

 

[Yooper920]

+1 on the fuel supply. Have a 25 year old JD 325 that acted similar this spring. A $20 fuel pump from Amazon did the trick.

https://www.greentractortalk.com/ is a good source of info

 

[Sherk]

It has been raining all morning here so I tore into the tractor again. I replaced the fuel line (with real fuel line) from pump to carb when I did the carb, the guy who gave it to me used a too short piece of clear tubing that looked like it had seen better days. Other lines are clean.

I wasn't sure how much fuel is supposed to come out of the fuel pump when I did the other work, so I assumed it was fine with something coming out. Maybe not enough though.

Today I pulled the fuel pump apart and the breather hole was completely plugged. Bunch of junk in that outside section. Cleaned it out with some carb cleaner and put it back together. I'll see if this fixes it and if not, get a new one ordered. Heading out on a business trip tomorrow so it will be a few days if I have to do that.

*Edit, it stopped raining long enough for me to try it out. Didn't start appreciably easier but didn't seem to need as much feathering when increasing RPMs. Ordered a new fuel pump.

Thanks all for your help so far!

 

[WillyBoy]

One more thing comes to mind. Older engines with "clear tubing" for fuel lines weren't designed for ethanol use.
If you're using ethanol free fuel, you should be OK or just replace the lines with something better.

 

[Sherk]

The clear tubing was a replacement run made prior to me that I fixed. That said, I always run ethanol free in small engines as it seems to not cause as many issues with the carbs.

New fuel pump fixed the issue! Starts and runs beautifully, no issues throttling up like before and fires right up.