Spin-on fuel filter take apart

[30Tournament]

Made a recent trip to the Abacos, running from Canaveral to Ft Peirce, OBB, Spanish, GTC and back, maybe 400 miles total. Had lots of fuel contamination issues, not due to bad fuel but from crud busting loose in the fuel tank on my old 1975 ChrisCraft 30' Tournament.

Hope the picture comes out. This is a Sierra brand spin-on filter, fits the Merc housing. Complete filter is on the left, opened filter on the right. I always assumed these filters had a large filter element, but note the height of the filter element compared to the housing. The element is not even 2" tall.

Time to polish my fuel and think about some Racors I guess, as these are my primary filters. I still think these spin-ons are fine for the average user, but for long distance cruising some larger filters are in order. The contamination was so bad at one point that the filter element inlet became totally plugged. One time the carb filter became plugged also, so I guess the spin-on became overloaded. I'm thinking about repowering with diesels anyway so Racors will be a good investment. Even with all the fuel problems, I was very impressed with this boat (first long cruise on this boat for us). Performance on the Bahama bank in the slop and in the stream was nothing short of amazing. It's a slow but extremely seaworthy and dry boat. I'm so impressed I'm taking it off the market and rethinking my boat needs. Our cruise speed was 17knts max, for about .7 nmpg average with big block GMs, my brothers boat is identical but has 240 Yanmars and he cruised at 20knts and about 1.25 nmpg on the same trip.

On the return trip, I had to run Indian Cay channel in the dark with 3' chop. I don't recommend this but we made it just fine.

[seahorse]

This link has a good article on filters and how they work

http://continuouswave.com/whaler/reference/fuelFilter.pdf

[cracker]

Alot of that data seemed pretty old since it was done in Feb 2004. Lots of changes since then.

[30Tournament]

Alot of that data seemed pretty old since it was done in Feb 2004. Lots of changes since then.

I found it an interesting and helpful article. I doubt much has changed in fuel filters since then. Maybe more people are using 10 micron or smaller filters now, otherwise I'd think the brands examined are the same as in 2004.

Looking at the marine catalogs, I see the Racor filter I want (turbine type, not a spin-on) is for diesel only, so I'll be keeping my spin-ons until the repower.

[micura]

The space is there to trap keep the separated water. Racors you can drain, but these you cannot, so it needs a reservoir for the water. Once this reservoir is full of water, no more water separation. Change ofter and you'll be allright.

[Wicked Awesome]

The space is there to trap keep the separated water. Racors you can drain, but these you cannot, so it needs a reservoir for the water. Once this reservoir is full of water, no more water separation. Change ofter and you'll be allright.

My mechanic strongly recommended the Yamaha OEM fuel filters over the Racor or Sierra units. He has one of each cut open on his desk. The filter area on the Yamaha unit is much larger than the Racor or the Sierra. Since the goal of a fuel filter is to keep particulates from getting through to the injectors or VST, the added filter area seems like a good idea. With ethenol blended gasoline I think you either have a little water mixed in with the fuel with no problems or alot of water mixed in and big problems. The water collection area on the Yamaha filter can probably solve the first problem. I think the bowl on a Racor isn't going to stop enough water to solve the second.

The Racor drainable fuel bowl idea has been around for many years. I always wondered why it wasn't widely copied by either the OEM manufacturers (Yamaha,Evinrude,Merc) or the aftermarket manufacturers like Sierra. Do they know something we don't?

[micura]

Racor has patents on their design. You can see them at uspto.gov. The important factor is the size of the filtration. The size of the filter only affects how long it will last before clogging and the max flow. Racors and Sierra are 10micron. Yamaha should be but has not published it. I have the Yamaha right now, but will consider using Sierra. Racors won't fit where mine are.

[seahorse]

The Racor drainable fuel bowl idea has been around for many years. I always wondered why it wasn't widely copied by either the OEM manufacturers (Yamaha,Evinrude,Merc) or the aftermarket manufacturers like Sierra.

For many years Yamaha sold the Racor type filter and bowl with their name on it. Check the Yamaha accessory catalogs. Now several other companies have come out with their filter and bowl designs since ethanol fuels have water problems.

I like the Yamaha tall 10 micron filter but it does plug up quickly if you have problems with your tank. That is why Yamaha says to change it every 50 hours.

The Racor traps many larger particles in the bottom of the bowl so they do not contribute to filter clogging and Racor has a large filtering area so it will last a long time. They do make a vacuum gauge to show when the filter is getting close to replacement time, but it is always a good idea to replace it at the required 100 hour service intervals that most outboards and inboards have.