Fuel problem?

1976 70hp evinrude it has a very rough idle and kills seems to be running rich i have rebuilt the carbs ( gaskets & floats) and fuel pump<br />compression seems good could the reed valves be weak or bad

Re: Fuel problem?

Sync & link can be critical on these 3 cylinder engines, is this correct on your engine? What are the compression numbers? Reed valves are a rare problem, fuel would be spitting back through the carb on the offending broken reed, and carb assembly. A running test on the ignition system would be a good idea. You have something breaking down, Compression, ignition, fuel, you have to detirmine which one. On an engine this age, I would remove the cylinder head, and have a look. There seem's to be a reluctance to remove a cylinder head on a 2 cycle engine. It is nothing but a cover, or seal, with no moving parts.It will save a lot of time, and searching in short order. Finding a scored clyinder, or scuffed piston will save a lot of time, and money in needless parts.

Re: Fuel problem?

the sync&linc look right not sure on compression numbers, all the coils fire <br />would there be anything in the carbs i missed on the rebuilding of them

Re: Fuel problem?

Many, many carbs rebuilt by wrenches inexperienced at carb rebuilding are still plugged up, putz.<br /><br />Details often missed are the orifices into the carb throat, float needle seats that leak, float levels, putting each carb back in the spot it was (critical on JohnnyRude twin and triple loopers).<br /><br />Your symptoms still sound to me like carb trouble.

Re: Fuel problem?

only thing i didnt replace were orifaces they did not come in the carb kits

Re: Fuel problem?

In the carb kit is at least one slightly domed metal disk, Putz. That is a replacement for the one on top of the carb throat.<br /><br />Remove the one on the carb. It usually requires drilling a small hole in it to get a pick into.<br /><br />Look in the hole. At the bottom of the carb throat you should see one or more tiny holes (orifices). Those are how fuel gets into the air stream coming through the carb throat. If you have soaked the carb body in carb cleaner you should be able to clean those out with air. If that doesn't work, use a small, stiff wire.<br /><br />The orifice in the center of the venturi is for high speed and the one just behind where the throttle butterfly contacts the throat is for idle. The one between is for intermediate speeds.<br /><br />To replace the disk (Welch plug) place the new one in the hole, dome up. Tap it with a hammer and a punch to expand it.<br /><br />Hope that helps.

Re: Fuel problem?

i see from a parts pic for these carbs there is a replacment oriface for that top part by the welch plug i haven't replaced would that possibly help <br />thay are calling it an idle oriface on the parts list