Fuel filters, pumps, and separators M25

[12Sail]

Happy Spring to all....looking for some insights on fuel filters / separators and fuel pumps for CD31 with universal m25.

I have a large "up and down" cylindrical primary filter / water separator right next to the fuel tank, at least i think that is what it is (seems large for a fuel pump). It is all metal, quite old in appearance, and about 6" high by about 2" in diameter.

Then there is the spin-on filter on the engine itself, but i'm not sure where the fuel pump is. Is it possible that the big cylinder is the pump, and i only have one filter? The PO took exacting care of this boat so i doubt that is the case, but as a 1983 boat i suppose anything is possible.

I'm sure pictures would help, and i will try to post some tmorrow when i visit the boat.

Thanks all.

[JWSutcliffe]

The larger cylinder adjacent to the fuel tank should be your primary filter. The fuel pump on 31s is typically mounted to a bracket on the starboard side of the engine aft of the injection pump. It should be easy to identify since it will have both fuel lines and electrical connections to it.

[Steve Laume]

If you follow the fuel lines, everything should flow into place.

From the tank shut off valve to the primary filter. Which in your case is the original Fram black and orange canister. Tot the fuel pump and onto the secondary filter mounted on the engine. There will also be a return line that goes back to the fuel tank.

One of the first things I did on Raven was to pitch out the old Fram filter and install a new Racor. It is far more convenient to change and you can see what is going on inside the sediment bowl. A vacuum gauge in the line is an excellent idea if you are replumbing fuel lines anyway.

This would also be an excellent time to figure out where all the fuel line bleeding screws are and how to use them, Steve.

[12Sail]

Excellent, thank you. You both confirmed my under-educated guess (thanks especially for identifying the "original Fram black and orange canister"...that's exactly what it is). The RACOR replacement of the Fram was one of the first things on my list of to-do's, but I think the mechanic didn't look under the port locker and see the Fram, thus thinking we had to "add" a Racor somewhere in the line rather than "replace" an existing filter.

Steve, was the Racor job fairly straight forward, or do you recommend a professional do the job?

I do love this site; thanks all.

[Steve Laume]

If you have tools and some mechanical ability it is a pretty simple job.

This would be a great time to replace all you fuel lines as well as the filters. Adding a vacuum gauge at the primary filter inlet would let you know if it is drawing hard and time to change filter elements in the future.

I have outlet and returns labeled on my fuel tank with a sharpie marker. If you sketch up a diagram before you remove anything it should be pretty easy to put back. You might need a couple of new fittings for the Racor filter as well as hose and clamps.

It is good to get to know your fuel system, Steve.

[12Sail]

OK, so the order will be fuel tank, vacuum gauge, Racor, fuel pump, secondary filter, injector pump, etc. Got it. Thanks Steve.

[Jim Cornwell]

Time and effort (and boat units) spent on the fuel system will reward you. At the time of purchase, Yankee's original tank had a thin spot that had been caused by the tip end of a wood screw gnawing away from underneath for years and years. It finally broke through during the delivery voyage from northern NJ to the Chesapeake. I was alarmed by the rate of fuel consumption before I discovered that most of it was finding its way to the bilge (and thence into the briny deep). Check the tank! Jim.