1978 OMC won't idle

A

Arent-ned508

Cadet
Joined
Mar 15, 2008
Messages
11
Hi,

Got my old OMC engine restarted after the head gasket was replaced. engine type is 15S10S; evinrude powerhead on a saildrive.
It ran a bit strange before this operation, and it still does.

First problem is that it won't idle. The engine will start only with the throttle halfway opened. It can run a little slower, but eventually it stops.

At higher rpm the engine stalls every few seconds (the old problem) and coughs.

I want to get the carb sorted, but am not sure how. I've attached a few pictures; suggestions are welcome. I can only find a screw to adjust idle speed. Is there a way to change the air intake?
In the picture of the float, you can see that the central part is damaged. Would that be a problem?

Another idea is that the timing is off. Suggestions on this are also welcome.

Gr, Arent
 

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tashasdaddy

tashasdaddy

Honorary Moderator Emeritus
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Re: 1978 OMC won't idle

the red arrow is pointing at the high speed jet. should be behind the drain screw. remove and clean. also get a carb rebuild kit, soak and clean the carb, you need the tool below to get the jet out. then follow the directions in the link below.

2.jpg


carb adjustments: http://forums.iboats.com/showthread.php?t=167352
 

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A

Arent-ned508

Cadet
Joined
Mar 15, 2008
Messages
11
Re: 1978 OMC won't idle

Hi,

Thanks for the info. I got to work with this, but I need a little more.

I didn't clean or rebuild the carb, just checked if there was any visible dirt, or something obviously wrong. Then I got started with your link.

Right now the engine runs smoothly at idle speed and reasonable, but a little rough at full throttle. Anything in between it coughs irregularly.
Only thing with the idle speed: it only runs ok when I set it very rich, and it dies immediately when the gas valve closes completely, so no idle with the gearshift in neutral position....

Still need a carb cleanup, or is this a fuel supply problem?
Any comment is welcome!

Gr, Arent
 
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