Could be the solenoid on the starter. Sometimes the post where the cable from the battery connects gets loose inside the solenoid and won't make a good contact all the time so that might explain the intermittent problem, if you can get any play out of it it's probably time for a new solenoid. I just had this problem with mine, and it worked perfectly when it was out of the boat, not sure why, maybe the jumper cables I was using to give it juice held the post in place.
Does it always start the 3rd time?
Last edited by jtnz; 05-31-2010 at 7:18 PM.