2003 Argo Conquest Shutting Down When Reaching Operating Temperature

[cralph26]

Hello out there!

I have a 2003 Argo Conquest equipped with a 20 hp Kawasaki liquid cooled engine model FD620D-JS12. I am experiencing an issue whereby the engine will start without issue and will idle perfectly until it reaches operating temperature. Once at operating temperature and load is applied (attempt to move) the engine shuts down. It will not start again without closing the choke. Once the choke is opened the engine shuts down again. If I leave the choke closed it shuts down due to flooding of gas I suspect. I changed out the gas in the tank with fresh gas and treated it with gas line antifreeze. This didn't seem to help at all. The air filter looks to be a bit dirty but not that bad. I checked the compression in each of the two cylinders and am satisfied that the compression is good. Both cylinders showed between 160 and 170 psi on the gauge. The carburetor most likely could use a cleaning. Is there anyone out there who has experienced something similar to this? When the engine shuts down it's like it loses spark or gas. I'm just confused as to why the engine runs perfectly until it reaches operating temperature!!! Any help will be greatly appreciated.

Thanks,

Colin

[chrisgt]

Will it drive at all before the engine is warmed up? It is possible for the coil to fail in such a way that it works fine until it heats up (actually a fairly common way for ignition to fail).
In my experience of those engines on mowers, the carbs are really picky. Does yours have the big accelerator pump? If that isn't working it'll basically die the second you try to open the throttle.
Those engines are also really picky about valve adjustment, you might be able to get the compression numbers up and more equal if you service them.

[cralph26]

Yes, I can drive the machine until it warms up. The first time this happened to me was after about 45 minutes of use and just before I got to my cabin in a remote location. The next morning I checked the air filter and changed out the spark plugs. I started the machine and proceeded back to my truck and again after about 45 minutes of use the engine died again. I had a really hard time getting out. The engine would start with the choke and after moving ahead a few feet it would shut off again. Also it is worth mentioning that the machine was in my shed for about 9 months without being used which I know is not good for the carburetor. I changed out the gas (87 Octane) and replaced it with high octane gas (91 Octane). I figured this was a good thing to do. Since then I have read that the 20 hp Kawasaki doesn't particularly like high octane gas. If it is a carburetor issue, I find it puzzling that I can use the machine without incident (lots of power no black smoke) until it warms up.

[chrisgt]

It's a small engine, it's probably fully warmed up after only 10 minutes of operation. Since it'll consistently run for ~45 minutes it could be a failing ignition module causing no/weak spark. One really easy test you can do is pull a plug wire and see how strong the spark is when the engine is cold, and then do it again when the engine is warm. Not the most scientific test, but if the spark is really weak when the engine is acting up, you may have found the problem. It's not the most foolproof test, but sometimes a good first step in diagnosis.

Engines designed for low octane gas shouldn't be effected by high octane gas, it's a waste of money*, but shouldn't hurt it.
Even though it's cold out, you could be overheating the engine or causing a vapor lock issue with fuel lines. Check to make sure the fuel lines run away from the engine and exhaust. Make sure the radiator fins aren't clogged and the cooling fan is working well. It may very well be the carb, but it pays to check the easy things first. As I said before, I've worked on these motors in the past, but never in this application, there may be a gotcha that I don't know about in an argo.


*Even when you use fuel stabilizer, octane levels degrade over time. Higher octane gas is actually a good thing for long term storage.