Best flowing fuel filter/water separator
 

Looking for the best flowing and filtering water separator that will fit stock merc. 454mag MPI's or 502 mag MPI's.

I would like to know this as well. I believe Sierra makes a 10 micron water seperator filter that replaces the Mercury 25 micron. I am not sure if the flow is equal or any draw backs going to a finer filter, like starving the engine or clogging the filter sooner.

Ayuh,.... The stock units will flow more fuel than yer motor can burn,....

Clean filters are the key,....

These are, in my opinion, the best filter out there for your application. http://fstperformance.com/

I believe you are correct. Those filters were OE on the Mercury 800's, 1075's and 1200's

Would you believe Mercury has a new filter? It actually looks pretty good on paper.

I'll find the part number.

If you ever cut open the stock OEM Mercruiser fuel / water sep filter you would be surprised. We have cut open 100's. They are poor quality. Especially after fuel sits in them for sometime.

They have a vinyl / rubber pad dead center bottom internally of the filter that deteriorates and turns like a black gel substances. Also they have poor sealing glue in globs around the metal end caps but not every filter has this.

Next important tip is look under side of the filter mounting pad you might be surprised in that area as well. Rust and or aluminum oxide build up and sometimes very heavy.

The middle portion of the filter mounting pad can form rust way up in that section as that is your fuel outlet portion after the filter. Just get an inspection mirror or take the whole mounting pad off to see if you have crap built up. Its easier to see when its off and of course turned upside down.

Racor with the metal base / water drain or Wix would be good choices.

fiter number
 

do u have a wix number by chance?

Not a fan of wix anymore.

For the money Sierra - very even spaced pleats, expoxy coated internally never any corrosion, no rubber or plastic or no glue that dissolves to jack with upper fuel system components.

Wix uneven spaced pleats, can corrode internally over time, and a plastic piece that forms to the spring that deteriorates over time. Prob my post here is going to create an argument. Sorry guys I cut marine fuel filters open daily and see the end results to know better whats poor, whats middle of the road and what holds up really well without issues. . .

Next upgrade is Racor and for I/O's boats --- YOU MUST have the metal bottoms NOT plastic bottoms installed on the Racor filters. CG approved is the metal bottoms for I/Os mounted inside the engine compartment.

Next the highest up grade is FST Filters. These filters years ago had another name until FST bought them out about 5 years ago.

Merc black side OEM filters is one of the worst quality filters you can buy, they corrode internally as well. Complete junk. Even if you cut these open when brand new,one will see how poor the quality is.

Last season for WIX for me that's for sure! One thing worth noting on the FST's is you need a new filter head for the stock MPI apps I think but that may have changed since I last looked.

Short version: Part Details
Longer: Part Details

I have been using the Wix 33405 filter, but my filter head has 1"-14 thread size. Anyone have any opinions on this filter? Seems to work ok but I have never cut one open.....

I use Wix 33405 and a 33418 (two feeds and pumps). Seem fine, look well constructed when cut apart; haven't replaced them in the last two years though :)

We use Wix 33225 Long , 33226 Short on the Stock Mercruiser apps , and the 33405 on the performance boats . I agree with BUP , I cut filters regularly to look at the Quality .
Not a big fan of Merc Stuff , cheap quality with high price. I prefer Wix and use some sierra . If Caterpillar made filters to fit our applications , then we would have High Quality Filters ! There stuff is very good . But as we all know , filters should be changed At Least once a year on our performance stuff.

Donaldson is an OEM supplier to Cat and John Deere.
they are a high quality option.

Jeff

Same here. Had a ton of varnished gas and sediment in the starboard gas tank of my Active Thunder after 11 years sitting with 70 gallons of gas in it. Rigged it with this Wix 24770 filter base and Wix 33405 14 Micron large capacity Fuel/Water separator with drain. ~$50 720GPH setup.
https://www.amazon.ca/Wix-24770-Filt.../dp/B000CSGT64
https://www.amazon.com/WIX-Filters-33405-Heavy-Separator/dp/B000CSEV64

On a side note... are you going to be out in the bay for the fleet week air show?

Reporting Wix 33225 just cut one open today - filter was changed for the start of boating season 2016. its about 1.5 years old - quality is NOT top notch bit not too bad either. . Plastic round piece that holds the spring is dissolving, Below the spring - a tad of rust internally forming because the outline of the spring rubbed the internal coat away . The Pleats are spaced fairly even but not as even as a Sierra that I cut open this past Saturday.. This 1.5 year old WIX 33225 is below condition internally compared to the cheaper price Sierra. This is not bad but the plastic piece dissolving I do not like period nor the bit of rust forming.. I am talking about WIX 33225 compared to Sierra 18-7944 Only for this post.

this must have been brought up before cause I cked my shelves last night and had two of each and then recalled seeing rookie post this before and purchased two right away and forgot about it. They were still in original packaging. That's the problem with a project that seems to go on forever. You forget what you already have in some cases. Anyway I went this route.

Yes, on Saturday only in my 22 Avanti.

Well be out there Saturday as well usually anchored upside of Alcatraz after lunch on Angel Island. If you see a beat up 272 Islander with a black Bimini feel free to swing by for a beer.

Sierra 10 micron short 18-7944.

Initially installed the longs on my '96 454 MPI; however, they contacted the OE lift (fuel) pump more than I'd like. Considering there's a warning decal right there that says not to use longer than a 3.5" filter for fear of fire etc. I reinstalled shorties.

I'm always willing to try something else though. Does anyone know if the FST filters will fit on the OE base? Their site says the filters are for their system. I can take measurements based off their info. but I have no idea what size the OE threaded post is. Nice that it filters down the 4 micron!!!