Ok, I take it when you say it won't catch you are saying that the engine turns over, just won't start.
If so then you can rule out the starter also.
Now, then turn the key to the on position without trying to start it. Make sure everything esle is off. Listen for a humming noise, it will only last about 3 - 5 seconds. If you don't hear anything then it could be the pump or a relay.
The pump is located in the tank.
The relay is located if the under hood fuse block.
To check relay look at number on it the look at relays around it and see if any match up if so just swap the 2 and see what happens. Just make sure you remember which one tou swapped so if it starts you know which relay you need to replace.