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Anybody felt this pain before?

Runs ok for weeks then after starting and after the choke opens up, it wont idle at stops unless at very high rpm for a few miles, then it's back to normal by the time I get back home.

The "good" news is that it didn't go back to normal my last drive and I can now work on it. The fuel bowl level was ok and there weren't any vacuum leaks but when I rev'ed it (since it wouldn't idle at low rpm) I saw gas dripping from the primary venturi/nozzle (hitachi dch-340 on a '79 luv). I forced/sprayed carb cleaner through both the primary main air bleed jet and a nearby hole (maybe an air bleed for the primary slow jet) in the throat until it came out the other hole and the primary venturi nozzle. It now idles again at low rpm (and the venturi nozzle is dry as it should be) but at high rpm/open-throttle, at the primary venturi nozzle I'm now seeing some gas passively spraying (ok) but still some gas dripping out. Should the gas never drip and always come out passively as a spray from the venturi nozzle at all speeds?

I'm thinking of removing the idle mixture screw and the anti-dieseling solenoid so I can spray and/or vacuum out all the primary passages in case there's still dirt in there. Any suggestions short of rebuilding the carb (which I need to keep for emissions reasons)? I'm not sure I could rebuild it any better than it's now running.

thanks

......ooops......I forgot to mention that even though it now idles ok at low rpm, the idle mixture screw seems to have very little effect. If I lightly close it, it still runs (barely) whereas it used to sputter out completely. Hmmmm......too many clues and not enough brains....

Have you recently increased the idle speed with the idle speed screw? If you have, the butterfly maybe open to allow enough airflow thru the venturi to activate the main fuel circut (booster). You will be past the idle port. You stated the fuel level is ok but the needle and seat may not be sealing well enough. Check for binding with the float or trash in the needle and seat. Check the ignition timing.

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1980 4X4 LUV

I'll have to check the rpm again. I did muck with the setting when it wouldn't idle (when the venturi was dripping a lot) but I thought I had set it back to 850rpm afterwards. Your explanation makes sense. I suppose that internal gas leaks could also produce the same result but I prefer your explanation.


The gas level in the bowl is centered in the sight glass. Doesn't this mean that the needle and seat are working properly?

I'm thinking that the only possible explanation for some gas still dripping out of the venturi nozzle at open throttle is that there still must be some dirt in the idle circuit air bleed passages.

thanks

I am having the same problem with my Hitachi carb. I can't find anything wrong with it and yesterday I went through the carb and did a complete soak and rebuild. I pulled every jet and cleaned them and the passages out and when I put it back on I had the same problem. you can hear the crackling and popping of the fuel puddling on the top of the butterfly and the engine is trying to suck it through. the fuel chokes off your idle air and causes the engine to not idle. I'm lost for a cause of the problem.

Fred 770...I am having the same problem as you....My 77 LUV is dripping/kinda spraying gas during idle and just today I went through the whole carb and cleaned and sprayed etc. The dripping is making the idle rough and liquid fuel can be seen on top of the butterfly in the primary chamber. I wish someone had offered you a solution cause I sure need it now. We had every screw, jet, orifice open and cleaned with carb cleaner but still the gas is not atomizing like it should. Don

Did you blow out or use a wire to clean out the air bleeds all throughout the carb? Also check to see if your base and top of you carb is warped.This can cause funny vacuum leaks that mess with the venturi effect in the carb.Check the mixture screws and see if they are straight,

Two things will cause fuel dripping at the venturi. Foat level too high, or the idle speed screw is open too far (idle speed too high). This could be the result of a vacuum leak somewhere and opening the throttle more to compensate. Or ignition timing too late, and again the throttle opened more to compensate. And--of course plugged idle passages like has been covered.