ok so i took apart my cbr down to bare frame and just put it together last night it does start for a few seconds then it shuts down. when i tuen the key on most of the time i dont hear the fuel pump turn on. what do you guys think the problem is? the battery is kinda s&#$ do you think that would be the problem? or something else

 

Will the engine turn over when you 'dont hear' the fuel pump turn on? It shouldn't if you don't hear the fuel pump prime.

Could be a couple of things:

- The wiring isn't making a good connection all of the time
- Your kill switch isn't working properly (even though it's in the 'run' position it may not have continuity)
- Could be one of the sensor's got messed up when you took it apart (i.e. bank angle sensor, kick-stand sensor, etc.) Did you mount the bank angle sensor correctly?

Have you tried jumping the dummy wires to see if it's throwing a MIL code?