metalmonkey47 Posted April 10, 2010 Report Share Posted April 10, 2010 So to keep it simple, my sunny has had a problem with a high idle since day 1. It likes to idle around 1000RPM cold, but as the engine gets warm it averages 1500-2000RPM. I've gone through just about everything and can't find anything suggesting a problem. Choke is okay, no vac problems those sorts of things. I don't believe it's an adjustment problem either. Ideas? Quote Link to comment
INDY510 Posted April 10, 2010 Report Share Posted April 10, 2010 Do you have an idle adjustment screw? .......... are you shure your choke is closing all the way? Why not just turn the idle down.......... and then use the choke until it warms up.... Quote Link to comment
metalmonkey47 Posted April 10, 2010 Author Report Share Posted April 10, 2010 Do you have an idle adjustment screw? Why not just turn the idle down.......... and then use the choke until it warms up.... Tried that. It won't idle high enough when cold. It stalls in a hurry. Makes it seem as if it's not an adjustment problem. Quote Link to comment
datzenmike Posted April 10, 2010 Report Share Posted April 10, 2010 Find the secondary vacuum diaphragm and pull up and down on the rod that opens the secondary throttle plate. The secondary may not be fully closed and air leaking in. . Quote Link to comment
metalmonkey47 Posted April 10, 2010 Author Report Share Posted April 10, 2010 Find the secondary vacuum diaphragm and pull up and down on the rod that opens the secondary throttle plate. The secondary may not be fully closed and air leaking in. . Makes perfect sense. That would explain the rough idle when the choke is closed. Quote Link to comment
datzenmike Posted April 10, 2010 Report Share Posted April 10, 2010 I bought a Z24 and swapped it in in the fall. Got it running the next spring and it had a 1,200 rpm idle. NOTHING I did would bring it down, I tried everything including re building it and gave up. Later that summer I was messing with it for something un related and the secondary snapped shut and it stalled because I had the idle speed and mixture turned down. I reset them and bliss. Never noticed that the secondary was open ever so slightly... doesn't take much. Quote Link to comment
metalmonkey47 Posted April 10, 2010 Author Report Share Posted April 10, 2010 I bought a Z24 and swapped it in in the fall. Got it running the next spring and it had a 1,200 rpm idle. NOTHING I did would bring it down, I tried everything including re building it and gave up. Later that summer I was messing with it for something un related and the secondary snapped shut and it stalled because I had the idle speed and mixture turned down. I reset them and bliss. Never noticed that the secondary was open ever so slightly... doesn't take much. I never would have thought of that. It makes perfect sense now that I think about it. I appreciate the help. This has GOT to be it. Quote Link to comment
metalmonkey47 Posted April 10, 2010 Author Report Share Posted April 10, 2010 So I check the secondary, and it IS closing and opening properly, so it's back to the drawing board. Quote Link to comment
datzenmike Posted April 10, 2010 Report Share Posted April 10, 2010 Well that's good... it's eliminated as the problem. Is the fast idle cam stuck? Its a plastic cam with steps on it and connected by a linkage to the choke. In the picture its the white plastic thing with the steps on the bottom. Once the chole warms up it should drop down out of the way and NOT hold the throttle open for a high idle. WD-40 the area and work all moving parts back and forth to loosen and lube them. . Quote Link to comment
metalmonkey47 Posted April 10, 2010 Author Report Share Posted April 10, 2010 hmmm... makes sense. I'll check that after I get off work. Quote Link to comment
datzenmike Posted April 10, 2010 Report Share Posted April 10, 2010 Here's a better shot of it. You can see the fast idle adjustment set screw against it. When the engine is cold and you step on the throttle to set the choke on, a linkage allows the plastic cam to drop of it's own weight and now is in the way when the throttle is released. The set screw sits on one of the steps holding the throttle slightly open and allowing more air in for a fast idle warm up. Once the choke warms up and opens the linkage pulls up on the fast idle cam and lifts it up out of the way allowing the throttle to close to it's proper idle setting. Quote Link to comment
metalmonkey47 Posted April 11, 2010 Author Report Share Posted April 11, 2010 Okay, I see exactly what you mean. I'll check it in a few if I get the chance. Also, do you know if the choke breaker diaphragm is designed to leak vacuum or release vacuum at all? Quote Link to comment
datzenmike Posted April 11, 2010 Report Share Posted April 11, 2010 The vacuum break diaphragm uses vacuum to pull the choke open for full performance acceleration when the engine is cold.The hose and diaphragm should not leak. Quote Link to comment
metalmonkey47 Posted April 11, 2010 Author Report Share Posted April 11, 2010 okay, so that didn't solve it either, so I just pulled off the carb. I'm working on rebuilding it right now. Quote Link to comment
metalmonkey47 Posted April 13, 2010 Author Report Share Posted April 13, 2010 And she's running again :) Idle's a little rough and needs adjustment, but it all feels better then before. Next task is the ignition switch. Quote Link to comment
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