Based on this post, I believe it is the Vacuum Switching Valve in the Engine bay (Since you already swapped the one in the Charcoal Canister)
https://www.clublexus.com/forums/gs-...r-fueling.html

You can buy one from Amazon

And here are directions to fixing it
https://www.clublexus.com/forums/sc4...ml#post9605117

I have never had the problem and have never changed the part, so I am just guessing at all of this, but it is my 2 Cents

 

Good call Double-D!

 

Interesting thought. But why only when I get gas and not everytime I try to start the car? I do appreciate everyone's help on this. This is an awesome forum!

 

If the valve is stuck open when you get fuel the intake is flooded with fuel vapor causing an extremely rich condition and making it difficult to start the vehicle.

I posted a link to this thread a while back when I cleaned mine and the throttle smoothness improved. I don’t believe I remember anyone commenting. It’s a very simple DIY.

https://www.clublexus.com/forums/ls-...procedure.html

 

SCBlack02: This is likely why you can only get it started after holding the gas pedal all the way down. Opening the throttle lets in max air to counter the flooding (with gas vapor). Those of us experienced with the carburated cars of old are well versed in starting flooded engines!

 

Tried your idea. Got gas, turned on key, hit the pedal to the floor, released, turned key to igniton (start). It popped, but then died. Then started up the same way (struggled but kicks in). As usual, no problems after that.

 

Don't release the gas pedal before or while turning over the engine to start.

Get gas. With key off, press pedal to the floor and leave it there. Turn key to start and turn over engine to allow fumes to vent through the intake and out the exhaust for a few seconds. If it doesn't start after the few seconds, release the key from the start position. Then try to start normally (turn key to start with foot off the gas).

Did you ever replace the vacuum switching valve in the engine bay per Double-D's suggestion? Seems like the culprit based on your symptoms.

 

After getting gas car won't start,same problem as other owner had...wondering if anyone knew why.thanks

 

just curious, when you filled the car, did you keep topping off the tank after it clicked?

 

probably did...next time I get gas I'll stop before it is full...I have already changed the cap.only time it happens..I just now took cap off,put it back on let it click a few times tightening it...car started just fine..thx for the tip...

 

I wish SCBlack came back and tell us what was the culprit for his problem. I really want to know.

 

Fuel can get into the charcoal canister when we overfill our cars…the fuel can damage the canister and it is extremely expensive to replace.

 

Did you try this?
https://www.clublexus.com/forums/sc4...l#post10980843

 

Here is a generic video on how to troubleshoot the problem

 

Im having the same problem only it has nothing to do with getting gas, all of a sudden Ill drive 25 miles shut engine off for anywhere from 10 to 45 minutes and crank it over and it stumbles, lights come on the dash and it dies, I then have to hold my foot on the floor before it will start. No check engine lights, weve recently dealt with an oil leak from the lower pan and the oil filter housing which is now repaired. This problem is usually random and does not always happen but does happen at least once on my way to work if I have to make any stops. I am going to try the recommendation above today to see what that does.