Idle speed question on '89 GT150

[MikeB0307]

We have an '89 GT150 Johnson, newly rebuilt. It idles/runs great on muffs but likes to stall at the ramp until warmed up, unless I'm constantly pushing in on the key to enrich the mixture. I believe the idle may be too low but I'm not sure. It idles about 1500 on the muffs. I've also rechecked the sync on the carbs. It runs great as soon as I can get it warmed up but will stall at idle at random times all day. Any ideas would be appreciated. I'd also like to know what the proper idle speed is on the muffs. Thanks!

 

[metriccrescentwrench]

Re: Idle speed question on '89 GT150

I'd also like to know what the proper idle speed is on the muffs.

There is no proper idle speed on muffs. Idle speed is specified for boat in the water, engine in gear (and boat moving, not docked or on a trailer). With that being said, off the top of my head your idle speed of 1500 on muffs sounds in the ballpark or maybe just a bit high.

It's normal to have to give a few shots of the primer as the engine warms up, these things are pretty cold blooded on the first start of the day.

 

[emdsapmgr]

Re: Idle speed question on '89 GT150

Follow Wrench's recommendation. Set the idle to between 650 and 750 when in the water-in gear. You may find the resulting idle on the trailer is at least 1200, but it varies depending on how deep your engine/boat rests when floating. The deeper the engine sits on the boat in the water, the higher the idle will be when running on the trailer.

 

[MikeB0307]

Re: Idle speed question on '89 GT150

Thanks guys!