Feanor Posted December 8, 2014 Share Posted December 8, 2014 So the other day my brat started idling super slow on me, like it was going to sleep on me. Sometimes it would idle slowly enough that it would quit. Before this started happening I had adjusted the idle speed so that it idled at a little below 1000 RPMs, but now it was idling around 200-300.. It's not overheating, but when it happened the engine was at normal operating temperature. I checked the oil and that is fine. I checked all the wires on the spark plugs and they were snug. I simply adjusted the idle speed screw so that it was back up to around 1000 RPMs, and it runs normally now, but at first (right after I adjusted it) the engine was hiccuping, or lapsing rather. What could be wrong with it? I fear that by simply adjusting the idle speed screw I'm only treating the symptom and not the cause of the problem. Quote Link to comment Share on other sites More sharing options...
Subruise Posted December 9, 2014 Share Posted December 9, 2014 check fuel filter(s) Quote Link to comment Share on other sites More sharing options...
DaveT Posted December 9, 2014 Share Posted December 9, 2014 Vacuum leak might do this. 1 Quote Link to comment Share on other sites More sharing options...
l75eya Posted December 9, 2014 Share Posted December 9, 2014 Hit that carb with a can of carb cleaner. Read them instructions. Can't hurt. Quote Link to comment Share on other sites More sharing options...
jono Posted December 9, 2014 Share Posted December 9, 2014 compression test, tappets ...resolved issues before Quote Link to comment Share on other sites More sharing options...
TomRhere Posted December 10, 2014 Share Posted December 10, 2014 Worn throttle shaft will do it too. Quote Link to comment Share on other sites More sharing options...
Feanor Posted December 11, 2014 Author Share Posted December 11, 2014 Thanks for the replies, I will try and troubleshoot it. The weird thing is though, that just last night it started idling really high. I adjusted the idle speed screw down again. Something is changing independent of the idle speed adjustment screw that is changing the idle speed. What could it be? Quote Link to comment Share on other sites More sharing options...
l75eya Posted December 11, 2014 Share Posted December 11, 2014 Might be debris floating around in the idle circuit. Sometimes blocking it partially, sometimes not. I repeat; hit it with some carb cleaner. Quote Link to comment Share on other sites More sharing options...
Crazyeights Posted December 14, 2014 Share Posted December 14, 2014 I had one old carburated Subaru where the idle mixture screw and spring would wind itself out over time and fall out. It was always just sitting right there so I could screw it back in. Quote Link to comment Share on other sites More sharing options...
lilySapphire Posted December 15, 2014 Share Posted December 15, 2014 You have a Weber on that bad boy? I had irregular Idle and found that my Brat was begging for a fuel regulator. They are fairly inexpensive, I think the one I got was like 30 bucks and it made a huge difference in the entire drive experience. I don't know if anyone else has feedback on this, but seemed to work for me. 1 Quote Link to comment Share on other sites More sharing options...
hatchsub Posted December 15, 2014 Share Posted December 15, 2014 Im voting a vacuum leak without seeing it. Ive had that happen many a time. Hitachis when running correctly are good carbs. The problem is most are on their last legs by now. And they are overly complicated. If you do end up finding its the carb i strongly recommend ditching it and all associated vacuum tubes for a weber carb. Quote Link to comment Share on other sites More sharing options...
Feanor Posted December 31, 2014 Author Share Posted December 31, 2014 Thanks for the input. For a while now I've been wanting to switch to a Weber Carb, so that will eventually happen. I'll hit it with some carb cleaner for now and see what happens. Quote Link to comment Share on other sites More sharing options...
naru Posted January 1, 2015 Share Posted January 1, 2015 So the other day my brat started idling super slow on me, like it was going to sleep on me. Sometimes it would idle slowly enough that it would quit. Before this started happening I had adjusted the idle speed so that it idled at a little below 1000 RPMs, but now it was idling around 200-300.. It's not overheating, but when it happened the engine was at normal operating temperature. I checked the oil and that is fine. I checked all the wires on the spark plugs and they were snug. I simply adjusted the idle speed screw so that it was back up to around 1000 RPMs, and it runs normally now, but at first (right after I adjusted it) the engine was hiccuping, or lapsing rather. What could be wrong with it? I fear that by simply adjusting the idle speed screw I'm only treating the symptom and not the cause of the problem. Sounds very much like the carb is flooding slightly because of a leaky or sticky float valve. Since you have an EA-81 this is fairly simple to check. Merely check the fuel level in the sight glass.(I love those) Quote Link to comment Share on other sites More sharing options...
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