Join Date: Jul 2000
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Re: Yanmar 2QM15/primary fuel filter
The 2QM and 3QM engines were supplied with an engine mounted 'guard' filter at 15-17然 'nominal' retention 'rating'. The 'guard filter' is the teeny filter that is mounted ON the engine; the only purpose of the 'guard' is to protect the engine fuel pumps IF any upstream filter fails.
For 'best' protection, there should be a 10然 (Racor, etc. type) filter that precedes the engine guard. If your fuel tankage is notorious for historically releasing 'slugs' of debris or you get your fuel from 'notoriously' dirty fuel depots (ie.: marinas), then the 10然 should be preceded by a 30然 nominal rated Racor type filter.
Simple Speak: put a 10然 'upstream' of the engine mounted 15然, if the 10然 plugs rapidly then put a 30然 upstream of the 10然 and/or clean out the tank.
Tank ---> 30然 (optional) ---> 10然 ----> 15-17然 (engine 'guard') ---> engine.