Ok so I recently purchased a clean 99 Integra shell, and a b18b1 complete swap ECU and all. I have gotten everything together and after double checking all my grounds I went ahead and tried to start the car. I had all my dash lights come on, and the fuel pump primed telling me the main relay is good. However when I go to turn the engine over the starter won't engage. I can hear the clicking coming from the engine bay but it won't start. The dash lights do not even dim. However if I do apply a 12v power to the starters ground, the starter turns right over and starts the car no problem. I'm trying to diagnose the issue and I'm coming up short. Any help is much appreciated.

 

try cleaning the ignition switch contacts.
dont worry about the springs, see page 2:

DIY Ignition switch cleaning - Team Integra Forums - Team Integra

if that doesnt solve it then do this:

Rebuild your starter for less than $20 - Team Integra Forums - Team Integra

 

Sounds to me like you need to clean up your battery to body ground. Also trickle charge your battery for a day or two to be sure u have a full charge. My problems have been battery rather than starter in the past.