19hp B&S - can't find idle mixture screw


Old 06-22-04, 11:43 AM
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Unhappy 19hp B&S - can't find idle mixture screw

I have a 5 year old lawn tractor with a 19hp B&S engine.
(model 42E707 type 2631-E1)

I now need to pull the choke out part way in order for the engine to run smooth. My manual shows an idle mixture screw but there doesn't seem to be one on my engine.
Please help.

I took the carburator apart and cleaned everything I could but there was no change in the performance.
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Old 06-22-04, 03:15 PM
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You likely don't have a situation whereas the twist of the idle mixture needle will do any good, but the needle (screw) is located just under the fuel pump (which, by the way, is incorporated with the carburetor). You likely have a situation where the main jet is plugged. This is located around the right corner (when looking directly at the fuel pump side of the carb) of the pump. Remove this jet, clean the holes, reinstall and this should take care of your problem. Let us know how it goes.
Old 06-23-04, 08:43 AM
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Thanks - I will try this when I get a chance.

Back to the idle mixture screw for a moment.
I've looked under the fuel pump and there are 2 holes in the carburator where my manual shows the screw should be. The hole on top is larger but does not go anywhere.
The hole under that is very narrow and looks like there is something at the end of it.
I bought a carb kit for it and none of the needle valves will fit in the hole. The hole also does not appear to be threaded. Is it possible that some part has worked its way out and been lost? There is definitely no screws visible to adjust.

Thanks again.
Old 06-23-04, 10:56 PM
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Hello dougsa!

I see you're in Canada. I'd be willing to bet that the carb is non-adjustable on canadian models. I think the hole is blocked off, probably a welsh plug in it.
Old 06-29-04, 06:17 AM
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I cleaned the carb again, this time using the air compressor to blow out all the holes. Put it all back together and it works fine.

Thanks for the help.
Old 06-30-04, 12:22 AM
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Glad you got it fixed! Thanks for letting us know how it turned out!

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