Ps-2 will not play any saved data from Gran Turismo-3

This means it's loading your Game Data. There's nothing wrong with this appearing on the screen, it's common and simply indicates that it's loading your last saved state.
If it's stuck on that for a long period of time and not taking you into the game, then you need to go into the Saved Data Utility on your PS3 and delete your saved data file for Gran Turismo 5. Something might be corrupt.
Gran Turismo 5 uses a lot of the PS3's power, so having longer than average load times doesn't mean something is wrong with your PS3.

Yes, GameStop and EB games both sell an adaptor you can buy, I believe it's around $20 that allows you to save and copy your data from the PS3. I have Gran Turismo 3 and I had just about everything in it on my PS2; I thought I had to start all over when I got my PS3 but I got one of these adapters and it worked wonders. Same applies for PS1 games.

Good luck and if I've helped you please give me a good rating.

Respectfully,

Don

1. try reconfigure memory card save block (not the game save) I play 5 game profiles & cards used with Grand Turismo 3&4 (2 cards auto-start & 3 cards don't! = 4 sony & 1 mad cats)
   
2. CLEAN YOUR LENS! My SCPH-30001 PS2 IS 10years Old & I clean Both sides of my Lens VERY CAREFULLY ! every 2yrs. & it still works great!
   

go to save settings check there could have hit wrong button

the data probably got corruptted if you turn off the game while it is saving. unfortunatley there is no way to fix this except to start over. i know... that sucks. it happened to me with guitar hero 3

some times the memory card are not compatible whit some games try another memory card

well if while its saving you turn off the system it will go corrupt just delete the file and restart

If this is Gran Turismo 4 you are talking about, then if you still have the save file on your memory card from Gran Turismo 3 you can transfer your credits and all your license data over to Gran Turismo 4. In Gran Turismo 4 go to Home>Status>and it should give you an option somewhere on the bottom on the screen to transfer data, I think you press the square button. It has been a while since I've played Gran Turismo 4.

Your question is somewhat confusing, using a playstation 2 memory card, will have PS2 game saves on it, how would you play PS2 games on a PS1 from the save, you can't. If you just mean you are using a PS2 card for a PS1, the way a PS2 card saves data is different to a PS1 card, so it probably won't work You can use your PS1 memory cards in the PS2. You can only use the PS1 memory cards to save PS1 games that you are playing in your PS2. You can't save any PS2 game data to a PS1 memory card

what may have happened is that the saved files for GT4 on your memory card have now become corrupt, and the disk when put in the suysstem is trying to read the data from the card, simply deleting your saved GT4 data from the memory card should allow the disk to play as normal.