I have a 2001 IS300, It had problems about a year ago with the evap system and I had to replace the overflow check valve. The current problem is when it is hot outside and the car is cold, or when the tank is full, the car has a lot of trouble starting, it takes a few turns of the key and a couple pumps of the accelerator pedal to get it to start. The car has a new charcoal canister and gas cap, so I'm not sure where to start to look for the problem. Any help is appreciated.

 

Any other check engine lights on?

If no, I would start with a thorough throttle body cleaning.

 

It is giving P0440, which is an evap leak. I checked all the hoses on the check valve and fuel pump this weekend and so far its not changed anything.

 

The hard start and evap are most likely (99% positive) not related.

You will probably have to have the fuel system smoke tested to fine the leak. Not something you can easily do at home unfortunately.

Did you try cleaning the throttle body? There are 6 idle air assist holes underneath the small rectangular plate on top of the throttle body that become restricted.