Hosed up idle air settings

[CaptainPuget]

I think I’ve screwed this up big time. My 1985 – 115hp inline 6 started dieing on me at idle. Very annoying around the docks; so I tried adjusting the idle air screws on the carbs. It idles better now (not great) but it won’t accelerate, bogs down when I advance the throttle. If I baby it through 2000 – 3000rpm it runs fine at high rpm. I’ve adjusted and adjusted but I can’t get to run right. <br /><br />What’s the procedure for this adjustment?? The manual is no help.

 

[Chris1956]

Re: Hosed up idle air settings

Captain, The idle screws adjust the fuel mixture. Opening (CCW) the screw richens the mixture. If it bogs or dies when trying to accelerate, the mixture is too lean. However a lean mixture idles better than the mixture necessary to accelerate quickly.<br /><br />Try this to adjust the carbs: Start with the top carb. Open the idle adjustment screw 1/8 turn, and try to accelerate. If it is smooth, you are done. If not, open the mid carb idle screw 1/8 turn and repeat acceleration test. Continue for bottom carb, and try to accelerate. Repeat top-mid-bottom carb sequence again if necessary until it idles reasonably well and accelerates smoothly. These motors are not hard to adjust, if the compression is balanced and the carbs are clean.

 

[timbo1963]

Re: Hosed up idle air settings

I usually find that if it is hard to adjust the idle mixture then it needs cleaned and rebuilt. Ask yourself, why did it stop idleing right? Might need more than adjusting.

 

[CaptainPuget]

Re: Hosed up idle air settings

Thanks for the responses, I finally got it back to running well. I blame the whole pain in the butt on bad gas from the Big Salmon marina in Neah Bay. 3 bucks a gallon is bad enough but to have the stuff screw up your engine is totally inexcusable. <br /><br />Anyway I got some good gas in it, set all three at 1 ½ turns CCW from lightly seated, warmed the engine and tried the acceleration test, adjusting 1/8 turn in sequence top, mid, bottom until it accelerated without bogging. Ending up with all three about 2 turns CCW. It takes off like a scalded cat now.