my 912UL powered KFIV backfires (and I smell fuel) when I pull the power to idle for decent and landing. If I keep a little power on it doesn't backfire (or at least not as much). It runs very well the rest of the time and will happily idle at 1500 rpm. I don't have a return fuel line ( installing one asap) but my KFIII didn't have one either and it never backfired. Thoughts are maybe the windmilling prop is pulling too much fuel into the engine making it run rich. Anyone have any experience with this?

Thanks
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