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Mercuriser 350 CID 1985 won't idle


ebizsearch's Avatar
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Join Date: Apr 2008
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VA

05-27-08, 01:51 PM   #1  
Mercuriser 350 CID 1985 won't idle

Rough idling carburetor. Rebuilt in storage for 5 years. Engine starts and runs good at 1500 RPMs and up. Appears to run strong on shore & out of gear with no load. BUT with Rough idle. Took carburetor down and soaked over night in carburetor cleaner and cleaned and blew out ports but with No rebuild kit. Left idle adjustment jet will starve engine if turned clockwise too far. Right idle adjustment jet has no effect it clockwise or counterclockwise turns are made. Engine smooths out if carburetor cleaner is sprayed down right barrel when running. What port or opening is stopped up or whatever is wrong? Any help please Itís a Rochester 4 BBL Quadajet

 
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thezster's Avatar
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05-27-08, 01:54 PM   #2  
Sounds like time for a full Carb rebuild.... Soaking in carb cleaner won't do a thing for the internal ports - and will damage your existing gaskets/O-rings.

 
Speedwrench's Avatar
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05-27-08, 09:50 PM   #3  
you should dissasemble that carb and then soak for about an hour with carb cleaner, not the spray kind. then blow out all of the passages with water followed by compressed air. install new gaskets and probably a new float. those are good carbs but must be adjusted carefully to get max good out of them. make sure to check that all of the vac ports are clean and flow air when blowing it out . the small brass rods comeing down from the top of the carb controle the fuel flow for idle do not use a wire or drill bit to clean the holes on them. check that the jets are not out of round also some times that happens with age or a bad batch of brass. carefully check the mixture control rods to make sure that no nicks or burrs are on them also. when reassembleing the mixture control rods make sure that the small ones move freely up and down with light pressure on them. if the piston binds that will cause a flat spot on accel. man it has been at least 16 years since I built a rochester.

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