i replace my engine on my 00 civic si.
the fuel pump is not kicking in when i turn the ignition switch on.
i added a crankshaft position sensor and a msd ignition box.
the crankshaft position sensor is one of the inputs for the computer so the fuel pump could run. the engine turns over but the fuel pump dont run at all. and there is not power going to the fuel pump power wire. the fuel pump fuse is good is a 15amp. also, the starter signal fuse. there is more fuses that operate the fuel pump including the main ralay. but the car was sitting for a week without being started. so what could be wrong. only the new things that i added. the car was running fine before i did the engine swap

 

As you know, the pump should come on for a second or so when the key is first turned to 'run'. Sounds like you're not getting power to the main relay, or the relay is bad.