JD 320 stalls when engine gets hot/warm

nate81 · Jun 29, 2013

I'm noticing that when I try to mow the grass on really hot days my 320 will stall out on me after cutting for a while....if i choke it, it'll keep it going for a little longer but will eventually totally stall. It won't start back up until the engine has cooled.

I unplugged both of the wires from the spark plugs and used a screwdriver to test for spark...i did see spark in both.

I took the gas cap off and i did see a bit of dirt/grime in the little hole on the inside of the cap...i cleaned that the best i could...i havent run it since last night, so i'm not sure if cleaning the gas cap fixed it yet.

Fuel filter was changed last year I believe, or if it wasnt 2012...it was definitely late 2011.

I took the bowl off the carb....there was hardly anything in the bottom of of it and the float seemed to move up/down freely.

BBO · Jun 29, 2013

You may need a new gas cap. Leave it loose and try it. Change the filter again. It is cheap...
It could also be an electrical problem with the coils. Does it run smooth with normal power, or is it sputtering?
Change the spark plugs also.

But the deal with the choke does seem to indicate that it's being starved for fuel.
Stay away from fuel with Ethanol...

nate81 · Jun 29, 2013

I'm going to the JD dealership this morning...i'll see how much a new gas cap costs. yesterday while cutting grass the mower died....i tried take the gas cap off and then i put it back on, but the mower still would not start.

I'm going to change the fuel filter today as well.

If i'm seeing a spark from the coils does that mean they are ok? It runs well with normal power, but it does not like to idle often...normally when i pull the throttle down to empty the baggers it will just die out on me and i have to restart.

Where do i get fuel that doesnt have ethanol? (edit: googled...found a mom/pop gas station that has unbranded ethanol free gas 5 miles from me)

nate81 · Jun 29, 2013

I picked up a new gas cap, fuel filter and two new plugs (even though i just changed the plugs back in april or may)....when i took the old plugs out they looked like this http://i.imgur.com/NDAJBhv.jpg

Should the different coloring matter?

I asked the mechanic at the JD shop and he told me as long as i see spark at the wire the coils should be fine...i'm hoping he's right because the coils are about $70 each, and i'd need two!

Its raining today, i won't be able to test the mower out and see if the new plugs, gas filter, and gas cap fixed my problem.

mfreund · Jun 29, 2013

You only need 3 things to run, fuel, spark and compression. I think you are ok with the electrical side of the tractor running, I would try different fuel. Plugs look good to me, no worries there.

I know this is given, but I will ask do, you have enough oil in the engine?? Another Idea, check to make sure that there is nothing obstructing the air flow around the flywheel. IE mouse nest under the top shields

BBO · Jun 30, 2013

mfreund said:
Another Idea, check to make sure that there is nothing obstructing the air flow around the flywheel.

And the air filter itself...

nate81 · Jun 30, 2013

I got some seafoam and ran it through the tank...i had abotu 1/4+ tank of gas and ran a few ounces...it still stalls but at least now the thing will idle...i'm thinking the idle issue is unrelated. I feel like its overheating.

Oil level is good, checked that first thing to be sure it wasn't the low oil cutoff.

Where/what is the flywheel?

I cleaned(checked) the airfilter and washed the foam pre filter around it and reoiled that.

The book says to be sure the cooling fins are not plugged....are those kind of like heat sinks? just metal fins coming off the engine?? Because i have a liquied cooled system would I still have cooling fins? if so...where are they!? i swear this engine was installed upside down, i can't get to anything!

I'm going to fill up with ethanol free gas today with some more seafoam.

Oh...the coolant level in the off-white plastic tank (reservoir?) tank is good...but i opened the radiator this morning and it seems low to me...but there is no fill line inside the radiator...how am i supposed to know how much fluid should be in the radiator itself?

nate81 · Jun 30, 2013

I just put two pints of water in the radiator....its not filled to almost the brim where the radiator cap goes on. Can i have too much fluid in there?

JD420 · Jun 30, 2013

I had a 320 that was doing the same thing after it was hot it would start acting like it was running out of fuel. I found the the fuel pump was going bad. Mine had a mechanical fuel pump mounted by the carburetor. When it starts running bad remove the fuel line coming from the fuel pump going to the carburetor and put the hose in a clear container and crank the engine and observe the amount of fuel pumping out. It should squirt good solid amounts of fuel. If it just trickles out check to make sure you have a good fuel supply to the pump. It should run out of the supply hose at a good rate.

nate81 · Jun 30, 2013

JD420 said:
I had a 320 that was doing the same thing after it was hot it would start acting like it was running out of fuel. I found the the fuel pump was going bad. Mine had a mechanical fuel pump mounted by the carburetor. When it starts running bad remove the fuel line coming from the fuel pump going to the carburetor and put the hose in a clear container and crank the engine and observe the amount of fuel pumping out. It should squirt good solid amounts of fuel. If it just trickles out check to make sure you have a good fuel supply to the pump. It should run out of the supply hose at a good rate.

You no longer have your 320? What happened to it? how many hours did you have on it?

The coolant in my radiator seemed low to me...while the overflow tank has been good. I'm going to try running it this morning to see if it stays cooler

JD420 · Jun 30, 2013

I believe it had around 1500hrs on it when I sold it. The only reason I sold it was to up grade to a larger tractor with a bigger deck. Mine was a great tractor lots of power and mowed very nice. Just needed something bigger.

jinman · Jun 30, 2013

Nate, I suspect that your fuel is getting hot and boiling such that you are getting vapor lock. The next time it starts to stall, try putting ice around the float bowl. I think you are on the right track with non-ethanol and Seafoam added, but you might also try a premium fuel. If your fuel supply line is getting hot, you might add line and re-route away from the heat source. Also, does your carb get preheated by the engine coolant? If so, there might be a temperature controlled valve that is not cutting off coolant when the engine heats up. I know some Kawasaki engines use coolant or exhaust gas to preheat the carb, but your JD service guy should have known if that was a problem on any models. Your problem just sounds like very hot fuel to me, maybe the non-ethanol will do the trick and have a higher boiling point. I'm no expert, but your symptoms sound like vapor lock to me.

JD420 · Jun 30, 2013

That's a good point I forgot about. Make sure your tractor has the metal heat shield that covers the muffler. The muffler is very close to the carb on that engine.

nate81 · Jun 30, 2013

If it were from the fuel getting hot and vapor locking...i should be able to test that for sure by riding it for a while w/ the gas cap off correct?

JD420 · Jun 30, 2013

I don't think the cap being off would make a difference since the cap is vented. Vapor lock is when the fuel boils in the carburetor bowl. Sounds to me it's running out of fuel. My experience with vapor lock occurs after you shut the engine off then try to restart not while its running. But as we all know anything is possible.

BBO · Jun 30, 2013

If the reservoir line is OK and you had antifreeze in the thing, then the radiator should be full.
Does the radiator cap seem normal? Something squirrely with your descriptions.

nate81 · Jun 30, 2013

the reservoir was fine, but when i opened the radiator cap, the coolant looked low...i was able to add two 16 oz bottles of water directly into the radiator before it got filled.

BBO · Jun 30, 2013

Could someone look up the total coolant capacity on the 320?
On my LX188 the total fill is only 2.2 quarts, so a quart low might cause mine to run hot.
Have you ever had a light for high temp?

I changed the coolant in mine after 17 years of use and it was a good project.
You will need to take all kinds of crap off to do it.
It's a good time to clean the outside of the engine.

nate81 · Jun 30, 2013

well it just ran for 35 minutes...thought i'd take it to my back field to cut...and it died again. no high temp light ever came on....just stalled right on out.