86 Johnson GT 150 High Idle after Rebuild

[gloveral]

Working on a 1986 Johnson GT 150 for a friend who just bought it. Just rebuilt carbs, replaced fuel lines, water pump, and bypassed VRO. Fired up engine tonight and once it got going it kept picking up speed to a very hight idle until I shut it off.

The tach does not work (of course) but the idle/running is high enough to make me nervous to let it run. Carbs are synched, all closed at idle position. Saw a thread on quick start as a possible culprit--does this motor have it--could it be stuck? I did disconnect a scissor clip connection for the VRO--at least what I saw to be the alarm line. Bad thing is the alarm does not energize when I turn the key on so I do not know if it is working either.

I suspect and air leak but all hoses are on and tight and sealed off VRO oil pump with vacuum line plug. I know that it will run at higher idle out of water on muffs but not this high. Is it possible that the VRO portion of the pump is shot and is letting too much air in?

It has turned into one of those doing it for a buddy projects that was more work than this "pristine" motor was supposed to need

Thanks

 

[mikesea]

Re: 86 Johnson GT 150 High Idle after Rebuild

check that the timing base is coming back to the rubber bumper,could have a linkage problem there

 

[gloveral]

Re: 86 Johnson GT 150 High Idle after Rebuild

Thank you for the reply. I went out and checked tonight and it is back against the stop--unforunately I broke the platic retainer that goes into the base of the trigger--another part needed!

Is it possible I am getting too much air through the Fuel/VRO pump? I have capped the oil line tightly--should I just replace with a fuel pump?

Going to go through link and synch again, but need to get the plastic linkage first.

Thanks,

Allen

 

[diver_down]

Re: 86 Johnson GT 150 High Idle after Rebuild

put a piece of transparent line after the pump to make sure you get fuel only but i don't think you would get enough air to make it idle too high. recheck carbs / fuel lines for leaks, check timing advance (BTDC, there should be a sticker with it on the powerhead or you can get it from the service manual). from what you say it sound like you are leaking air through somewhere.

 

[emdsapmgr]

Re: 86 Johnson GT 150 High Idle after Rebuild

After any carb rebuild, a sync and link should be performed-as shown in the service manual. Parts can move slightly when reassembled. It is possible that the carb roller is resting against the throttle cam at idle. It should not touch it at idle. This may be causing the throttle plates to stick open just slightly. They must be closed at idle. The idle speed on this engine is set by adjusting the idle ignition timing-has nothing to do with the carbs. You should see idle rpm's in the 1100 range when on the trailer in neutral. Set the actual timing when the boat is at normal rest-floating in the water. Should be 650-750 rpm in gear, idling.