Old 06-17-11, 12:05 PM
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Join Date: May 2011
Location: usa
Posts: 10
Unhappy Misfires

I have a Bunton mower with a 31hp B&S engine 3cyl. and when I'm mowing every time I hit a bump the engine misfires or backfires, what could possibly cause this. It runs smooth other than I hit a bump and shake mower
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Old 06-17-11, 01:08 PM
bontai Joe's Avatar
Join Date: Apr 2004
Location: Pennsylvania
Posts: 592
Here is my guess: When you hit a bump, the float in the carb bounces and either momentarily allows too much or too little fuel into your engine, probably too little. Get past the bump and back on flat ground, every thing smooths out, right?
Old 06-17-11, 01:29 PM
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Join Date: May 2011
Location: usa
Posts: 10
It stops misfiring after the bump is there any thing can be done since it only started 3 weeks ago, 4 plus years and it never did it
Old 06-17-11, 09:09 PM
cheese's Avatar
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Join Date: Jul 2001
Location: USA
Posts: 16,814
Water in the carb will cause this (the water is heavier than gas, so it sits in the bottom of the carb away from the jets, but when you hit a bump, the water sloshes up to the jet).

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