when i pump my car with gas it has problem turning on it take like 2 tries to turn on.....normal days with out having to pump gas the car turns on normaly i have no clew what it can be its a 2002 lexus is300

 

Sounds to me like the fuel pressure in the lines are falling off when you unscrew the gas cap. Not exactly sure how this works but some cars have a one way valve to help keep fuel pressure after the car is turned off so it starts up quicker next time. Do you know if it will do this if you just release the cap and didn't actually fuel up? Regardless, try letting the pump prime a few times before starting to see if this helps. If it does help, it sounds like your fuel pressure is dropping off. It might not actually be the fuel pump. Hopefully someone more knowledgeable chimes in to what it could be.

I had a Mazdaspeed3 and there was a one way vent line to the gas tank or something that went bad. When I would go to start the car after filling up, it would idle like crap for about 60 seconds. It was a cheap, $10 little plastic valve, nothing major.

 

That is definitely interesting... The fuel tank is pressurized to a whopping 1 psi, so I doubt that is the issue... Also, fuel pumps in the IS's don't prime, they only run while cranking and running...

Again, interesting problem... I might do some research into that, not sure if I'll find anything though...

 

Thanks for clarifying.

 

Mis300 ill try pumping it next time.....mitsuguy ive been searching around i havent found nothing yet dont want to take it to a mechanic yet with me having an idea im not a easy person to get jipt off

 

I got my fuel pump replaced and my car wouldnt start at all. It could be the fuel pump relay?