I bought a hardly used Kymco Mongoose 50 for my son. It was garage kept and not ridden much. I test drove it this September and it started and ran fine. I stored it in my parents barn until this past week when we gave it to him on his birthday. It started up again and we rode it a bit. I started it tonight and we were riding for a little bit when it just shut off and I couldn't get it to start. I let it sit for a little while and was able to get it to start and let it idle for about 3-5 minutes when it quit again and I can't start it.

Is this most likely a gummed up carb? It didn't seem to be since it was originally starting and running fine under different throttle positions.

Any thoughts would be appreciated.

Thank you!

 

Can be all sorts of things, blockage in fuel pipe, blocked tank breather, float set so the needle hardly opens, water in carb, faulty spark plug or other ignition component (probably not CDI), or no oil in engine so it seizes once warm. As you can't start it now, check for a spark, if there isn't one, problem is ignition, if there is, then the problem is probably fuel related.

 

I'd start with a good carb cleaning.

 

Ok, just a quick update. I swapped the entire carb for a replacement with a manual choke. Fired right up. We rode it for a while the past few days, but then all of a sudden, we started it yesterday and had it idling. My son gave it gas and then it died. Wouldn't start back up. Let it sit over night, and started it this evening. Same thing. It ran right away, but then it died, and it won't start up. Definitely a fuel issue, but it's weird that it was running fine for a few days before starting up again. Any thoughts?

 

Dirt in tank blocked first carb, all it needed was cleaning, dirt in tank has now blocked second carb, either keep on buying carbs, or clean them and the tank out and fit an in line fuel filter.

 

Thanks. That would make sense except when I took apart the first carb to clean it, it wasn't too dirty. It was actually odd how clean it was. I even removed the the jets, cleaned them (I got a pack of jet cleaning rods as well), and the needle valve, but nothing too bad. I will say the main jet did have a little build up in it, but that was it. I only swapped carbs after disassembling the first because I was reading that a lot of people were having issues with the automatic choke system, so this replacement was recommended. I did have to swap the jets over to the new carb, so they are cleaned before reinstallation.

I will pull it all again I suppose.

Other than draining the tank, how do I go about cleaning the inside of the tank?

 

Take it off and give it a good shake.

 

Ok, so I replaced the pilot jet since I pulled everything apart again, and I saw it was plugged. I couldn't break it loose with my rods even after soaking, so I replaced it with a new factory jet. I also drained the fuel and added fresh treated fuel. The spark plug is on its way (had to be shipped from another store), but I'm getting spark, so I can't imagine it's that. The plug did look to be in rough shape, so I think it might help. After this, if it doesn't start, I'm at a loss. I checked the fuel flow also, and it doesn't look like the fuel filter is the issue, either.