150 HP Johnson, few questions

[rsm688]

Well my dad has an 86 Ranger bass boat with an 86 (I believe) Johnson 150HP motor on it. Anyways, the boat runs great once it gets going but we have had some problems with it starting and starting from stop lately. It seems that the boat wants to die when it starts and is idling when it has just started up, also when going into forward and first starting off it seems to bog and die some of the times. After the initial get go and the boat starts running if you shift into neutral it will idle just fine but if you cut it off it starts back the same way. Any ideas on what this could be?



Thanks,
Spencer

 

[emdsapmgr]

Re: 150 HP Johnson, few questions

You could have two issues. 1. If the idle rpm is too low, you will have trouble keeping it going. Needs to idle at 650-750 in gear when at normal level in the water. If too slow, it will die and can cause problems like you describe. 2. If one or two of the carb idle circuits has dried fuel in it, it will not idle properly. Do you know the last time the carbs were rebuilt?

 

[rsm688]

Re: 150 HP Johnson, few questions

I'm not sure if they have ever been rebuilt, if so its been at least 5 or 6 years. We have owned the boat since 98 and got it from his good friend who was the original owner. Basic maintanecne like plugs and all have been taken care of but no carb work that I know of.

Where are the carb idle circuits located at? I will pull them and use my air gun to spray some air in them and clean them out.


Also, what's the best way to tell the RPM's of the motor if it does not have a tach? Or I believe the tach is not functioning as well as with the speedometer. The idle RPM sounds likea good idea as it runs great when it's going, it will cruise at 45 smooth as can be all day long but just has trouble when starting and idling when it has just started up.


Thanks for the help,
Spencer

 

[rsm688]

Re: 150 HP Johnson, few questions

alright boat has a tach so I am going to check idle RPM this weekend and see what it's sitting at.


any other ideas?


Thanks,
Spencer