I just got a bass boat, an 89 Ranger 364V with a Johnson GT 150.  The boat is litterally in perfect condition.  We took it out for a test ride with the previous owner and it ran fine.  First time we took it out, all was fine with getting it to the ramp and launching it but the cranking battery was dead.  We fished around the ramp for about an hour and then left, caught a few too.  So I charge the cranking batery and headed out yesterday.  The battery is fully charged and the motor will trim with ease.  The problem is the motor won't start.  I think I found my problem and that is that I wasn't pulling up on the plastic bar to the right of the throttle and putting it into the run position .  Any input on other possible issues?  Thanks guys.

The GT motors will start better if you have the top of the motor level. 

Push the key in and hold it in that position to activate the choke when first starting it.

will it turn over and wont fire? or does it litterly do nothing what so ever.  if it wont do anything check the wiring to the ignition switch.  i just got done putting in a new ignition switch.  if it will turn over then check the spark plugs, fuel lines.  if that doesnt fix your problem then id go see if a mechanic could take a quick look at it.

It will rumble, but it will stop after about a second.  I think I know what to do now though, just move the handle to the right of the throttle up before turning the key.

push that handle all the way up which should put the boat in fast idle.  let it run at about 1500 to 2000 rpm without the prop engaged to get the motor warmed up.  after that put the boat in idle and if it shuts off after a few seconds in idle then do the fast idle for another minute.