You might check that bulkhead connector by wiggling it, but your description really sounds like what happens with simple loose or dirty battery cable connections. After sitting a little while, they will often make sufficient contact to pass enough current to run a few lights or the radio, but the connection will be broken from the stress of higher current demands as in running the starter.
To find the break, when the problem is occurring, use a test light or voltmeter and start right at the battery terminals and measure the voltage. The readings will be more accurate if you leave the head lights turned on, even if they don't work. If you find full 12 volts, move the negative lead to the body, then the positive lead to the starter. You're looking for the first place where voltage is lost. When you find the first point where voltage is missing, you just passed over the break in the circuit.
Monday, February 6th, 2012 AT 3:11 AM