I started to wire my engine up today.I'm having problems with the wire that runs the starter solenoid. It seems to have low voltage and will not work the solenoid. When I turn the key.It will click like a dead battery. I ran a jumper wire from battery to solenoid and it starts right up. Not a dead battery. This one has got me stumped.

Weeelllllll I have been in my barn every morning at 3am until time for work trying to figure out why one of my 454 mag mpi's would crank but pump would not prime or buzzer sound so no start. Not to mention a lost full day Sat and Sun...
fuses good, relays good and Volt gage worked too... after tracing the wires and testing each wire in the harness that has anything to do with the relay's starter, grounds etc.etc.etc.
It was one freaking 12v purple wire connection in a 7 wire plug way back in the corner of the dash...Seperated the plug cleaned what looked like a perfect plug and all is good... may not be your issue but only takes a little (crap) to screw up an electrical circuit..I am here to tell ya...

Grounding problem?

mine did the same thing .it end up being the seinod
http://bpi.ebasicpower.com/c/MER10G/...for+Mercruiser