Runs but won't Idle.

[brownhunter]

I have been helping a friend of mine. He has a 1976 inboard/outboard 140 Merc Cruiser. He had the carb cleaned and rebuilt. The guy who did it, set the carb a lil rich and higher idle. Which should mean to lower them if it was running to high at idle. Timing is good ect. The problem: It will not stay running at idle. The books says for it to idle at 500 to 600rpms in gear. Well it only runs at about 750ish barly. Best at 800 850. Basicly you have to gas it a bit to keep it running. It runs fine and great otherwise. You would think that by taking it out of gear it would run at higher rpms, but it dies. The gas is good and new.

Any ideas? Fuel pump? but it is getting gas. idk how they work exactly but maybe it not working well at such low throttle??? or do we adjust throttle linkage from shifter? but this doesn't make sense.

 

[Oshkosh1]

Re: Runs but won't Idle.

The books says for it to idle at 500 to 600rpms in gear.

That's in gear, IN the water...
OUT of the water, set it around 700 or so.

You can set the mixture on the carb itself, the idle is a function of the linkage. Don't set it rich...set it right.

You need to get a vacuum gauge on it, tweak the mixture to obtian the highest reading, THEN set the idle in the water tied to a dock.