!0 Micron vs 21 Micron Fuel Filter

[spbutler]

Which filter should be used for a 1995 225 HP Evinrude?
Sierra sells both a 10 and a 21 Micron to replace the Evinrude/Johnson 502905 fuel filter.
Mercury suggests that a 10 Micron fuel filter could run a motor lean and cause damage due to overheating for their Mercruiser engines, so they stick with 21.

[BUIZILLA]

21 will let the rocks thru

[Bruster]

But they will be really small rocks.

For example:
A human hair is about .003 in diameter.
A micron, short for micrometer, is a unit of measurement equal to one millionth of a meter. A micron is actually 0.000039 of an inch.
21 microns is .000819" or about 1/4 the size of the average hair.
Really small rocks.


21 will let the rocks thru

[VectorPat]

We run 10mic filters on F350s without any risk of too much vacuum. Yamahas 10mic flow 90gph so it should be an issue with you motor. I far as I know most current Mercs have a canister style filter in the engine. Too many filters will cause vacuum issues. With as much crap thats getting in fuel now I would run a 10mic and make sure to change it often.

[markt111]

I run 21 micron a s I am carbureted and the jets will let those small particles thru to burn compared to a small injector orifice

[benski]

You could put a vacuum gauge on whatever filter assy. you choose to run and see when she's starting to clog, but that might be window dressing. 21 for carbs, 10 for:iagree: FI.