scooter does not always start when warm By cometman (Read 618 times)

[cometman]

I have a 2007 150 scooter w/GY6 157QMJ It always starts and runs flawlessly when started cold, if I ride it about a mile and let it sit for about an hour, it may or may not start again. When I come back hours later it will start right up like nothing ever happened. I imagine that I smell raw gas and it might start after grinding with full throttle open. This is a hard problem to diagnose because it never happens at home.
Any thoughts or ideas would greatly be appreciated.

[jhbietz]

Along with Dr Jr recommended you should also check the vacuum operated fuel shut off valve. It is ether on the bottom of the fuel tank or on the frame of the bike. It will have 3 lines hooked up to it if its one the frame. One coming from the tank, one from the carb and one vacume line. If its one the tank it will only have the vacuum line and the line to the carb. If this valve gets sticky it will allow fuel to continue to flow into the carb after the engine has been shut off. The needle and seat in the carb can leak a little and the carb will flood. To check the valve, warm up your scoot, shut it off, remove fuel line from carb and place it in a tin can. If fuel continues to flow over and above what would be in the fuel line your shut off valve is bad.

[Bashan]

Both of the above are spot on and I've experienced both of them first hand. In fact, I had so much trouble with the vacuum fuel valve I replaced it with a manual valve. I've had a great deal of trouble with Dr. JR but I can't seem to find a way to replace him , he is right about the electricals heating up and acting persnickity though. I've also had mal-adjusted valves cause those symptoms, you might want to check that. Here's a checklist that you can look through for assistance. Rich