merc 1150 idle crazy

[penguin]

my 72 merc 1150 outboard, will start and idle fine out of the water w/ the earmuffs on. put it in gear, no problem. Put the boat in the water and it is a different story. In the water idle is low and will not idle in gear.....Now i know people say "turn up the idle screw" But out of water it idles at 2200-2300 rpm, can anyone help, thanks

 

[dick]

Re: merc 1150 idle crazy

Hate to say this but you won't be able to due much.These in-line Mercs have a problem where the cylnders become tapered (the bottom part of the cyl.is bigger then the top )This causes the engine not to draw in enough fuel/air at idle.Out of the water it will idle but put in the water where you have back-pressure it won't.You can have good compression but still have this problem.Short of a major rebuild or getting a newer engine you can't due much but jack up the idle and slam it into gear, but I don't recommend it.

 

[Elmer Fudge]

Re: merc 1150 idle crazy

If it's not a fuel delivery problem it's possible the choke shutters may be in need of adjustment. This solved a similar problem which i had a while back.

 

[Gold Bear]

Re: merc 1150 idle crazy

davette <br /><br />On each carb close the idle mixture screw until they lightly hit bottom, then open up each one 2-1/2 turns.<br /><br />Out of the water, adjust the throttle /idle speed screw until the engine idles fast (about 1,000 rpm's).<br /><br />Once in the water, re-adjust the throttle cable screw so she doesn't stall when you drop it in gear (approx. 600 rpm's or best she will do).<br /><br />You can try the idle screws at 2 turns, and if she stalls out of the hole then open them up a bit more til she doesn't stall.<br /><br />Good Luck,<br /><br />Gold Bear

 

[Kenny Bush]

Re: merc 1150 idle crazy

Also get a timing light and check your idle pickup timing. May need to adjust linkages also...