Fuel water separator recommendation

[Starscream]

+1 on the rivnut recommendation. I use them everywhere, with a similar installation kit. They also make rivstuds, which are the opposite idea, leaving you with a threaded post sticking out of the surface you are working on, but I haven't tried those.

Mounted the filter yesterday using M10 bolts and rivnuts. It's under the cockpit enclosure but will be exposed to the elements during travel. It also gets splashed a bit under power, which I don't love. But it should be waterproof. No leaks, and worked well on a short test run. The primer bulb that leads to the motor is in the cubby with the fuel tank, just to explain why there are three lines coming from the starboard cubby in the photo.

Oh...and DON'T order those elbows from Grainger that I linked to a few threads back. Total mistake to order 3/8" threaded fittings for a fuel system using 3/8" barbs and 3/8" fuel line. The threaded fittings are 1/4", of course, and I totally knew that. The fellow at Grainger was great, tracking down his last three 1/4" MPT to 1/4" FPT brass elbow fittings in stock, at about $3 each, and restocking the 3/8" elbows.

Any concerns about the quick-connect facing upwards like I have it? Don't like the idea of water pooling there, but it's certainly the best arrangement to minimize strain.

[OverEasy]

Hi StarScream!

Looks like a nice location!

Yeah, I’ve considered the Rivstuds but could only find them in ferrous steel, not SST, brass or Aluminum (not sure I’d trust an aluminum stud much anyway on anything less than 3/8 UNC… but that’s just me )

One thing to consider with a QD arrangement like that is the potential for thermal fuel expansion leakage when the QD is removed.
Filters flow in both directions so any residual fuel in the system between the QD port and the engine could foreseeably expand (sunlight, warmer air, etc…) and leak out and potentially drain into the engine well drain… In a former life I’ve been inadvertently caught out by that sorta thing… .

I can’t tell from the photo if they are the self-sealing type or not.

If the QD isn’t self sealing one could maybe splice in a a small shut off valve or something on the filter side or change to double sided self sealing QD? Just a thought….

Best Regards,
Over Easy

[Starscream]

A few weeks into operation: everything working perfectly, switching tanks is an absolute breeze, and nice to be able to see clean fuel in the cup.

Now I'm thinking of using the second fuel outlet to run to a second primer bulb and shutoff valve, so that I can refuel the dinghy/kicker motor right from the main tanks. Maybe that's too creative, but I really hate gassing up the kicker with a gas can.

[Starscream]

Hi StarScream!

Here’s a copy of our drawn out fuel system schematic:



Sorry I plum fergot ta take a picture of da setup on da boat… my bad.

I’ll try ya take one this weekend an post it.

Best Regards
Over Easy

I was just cleaning up the garage and I found the installation guide for the Sierra filter. In small print it says that for outboard motors the filter should be installed BETWEEN the primer bulb and the motor.

That's not how O.E. or I have it currently installed!

Seems to work just fine tho, does anyone know why Sierra would have this requirement?

[OverEasy]

Huh? ….Nuts
It’s been working fine……

[Starscream]

I found an excellent use for the second supply connection. I added a second primer pump and length of fuel hose, which will be coiled and hung up close to the filter.

It makes for a very easy refill of the Honda 2.3 kicker motor, yes, but even better was the end-of season drain-out of the main tanks. A couple of squeezes of the primer bulb, with both tank valves open, and the remaining fuel in the tanks pumped itself into the portable tank on the ground. A quick transfer into the Pathfinder, and not a drop spilled. That was the cleanest, easiest end-of-season fuel job I've ever done.



I have another leftover 3/8 fuel line that I just slip-fit over the filter's drain connection, and that worked to drain the filter, but it did leak a couple of drops. Not sure if I need to downsize the line or actually clamp it on with a hose clamp.

Another season in the books. Haulout day 2024. Sad.

[StellanFoxworth51]

I need to purchase a fuel water separator for my fuel system install on my 26D. I see ebay and amazon have many that are inexpensive, but would they be a good choice? They seem to be Racor knockoffs. What do you use? Which would your recommend for use or to shy away from?

I'd stick with genuine Racor if budget allows—they're reliable, well-supported, and proven. Some of the cheap knockoffs on eBay/Amazon might work short-term, but quality and filtration can be hit or miss. For peace of mind and engine protection, it's worth investing in a trusted brand. Also, make sure whatever you choose has the correct micron rating and a clear bowl for visual checks.

[Starscream]

I was just cleaning up the garage and I found the installation guide for the Sierra filter. In small print it says that for outboard motors the filter should be installed BETWEEN the primer bulb and the motor.

That's not how O.E. or I have it currently installed!

Seems to work just fine tho, does anyone know why Sierra would have this requirement?

So I figured out why the Sierra manual asks for the bulb between the tank and the fuel filter, instead of after the filter. Experience backed up by a discussion with Microsoft CoPilot.

Last winter I drained the tanks through the 2nd OUT connection, though a 3/8" drain line and primer bulb and shutoff valve to a tank on the ground, which siphoned out most of the gas in the tanks. Drained the fuel at the bottom of the separator, and fed it to my old car. Springtime: add 5 gallons of fuel to one tank, open the valves, squeeze the primer (which is between the filter and the motor) and...nothing. Not a drop of fuel into the filter. Not sure what would have happened if I had cranked the motor in this situation, but there's a lot of air in the system upstream of the motor for it to deal with.

The solution was to use the drain line: open the valve at the end of the line to allow air to escape, and squeeze the drain primer bulb. That created just a bit of suction to get the fuel up out of the tank and siphoning slowly into the filter. It took a long time though, but of course it would have been faster if I had filled the tank to a higher level. In retrospect, mounting the fuel separator BELOW the tank level would have been smart. I'm about level with the half-way mark on the tank. Once the filter separator had siphoned full, close the drain valve, stow the hose, and launch. Started and ran like a champ.

With the primer bulb before the filter I could have forced some fuel into the separator without haveing to create so much suction, but I still would have needed the valve on the drain line to be open to allow air to displace.

So now, I think I'm going to move the primer bulb back to the starboard tank, and add a second primer bulb on the port tank.

FWIW the drain line also serves as a great way to add fuel to the kicker motor, something which was awkward at best and dangerous at worst, is now super simple. Get the siphon going with the drain primer bulb, fill the tank, close the valve.

[OverEasy]

Hi StarScream!

We both have our fuel filters at roughly the same relative position to the tank… mine might be a tad lower than the mid line of the fuel tanks but I have the lines to the fuel selector and bulb run to the top of the stern wall so they are both very easy to reach from the helm seat while underway (which has actually come in handy a couple of times). I did notice you have a somewhat larger filter size than ours.

My experience with priming the dried out system at the beginning of season has been about 15 to 20 bulb squeezings which I suspect would be the same regardless of the bulb location in the line structure. I haven’t ever had to ‘vent’ the end of the system to fill the line and filter to the engine. I’ve never tried to prime the fuel line by using the engine fuel pump.. not sure that would work.

If we were to ever get a nice gas kicker like yours for Over Easy or a dinghy I’m sure gonna copy your idea/concept for that fill line!
What a great idea!

Hope you have a fantastic 2025 season!

Best Regards
Over Easy

[45Plus+]

A late entry to the discussion and a couple of questions to add to the topic.

My fuel filter/water separator (an R12T) is lower than my gas tanks and my primer bulb is between the tanks and engine. The instructions that came with my filter said to fill the lower cup of the assembly with fuel then screw it onto the base. That worked just fine and the engine started even though there was no fuel in the fuel lines (all newly installed) - apart from what might have been forced into them by the primer bulb.

This whole discussion got me thinking about what would happen if I inadvertently allowed the engine to suck a tank dry. Would it draw in all the fuel in the lines and the filter/separator? If so, hopefully it would not pull whatever water that happened to have accumulated in the filter into the engine (?). And, to prime the fuel line/filter system when I connect up fuel tank no. 2, would I have to add fuel directly to the filter/separator cup again to get fuel to flow? I've been carrying an expensive 1 litre can of gasoline in the boat just in case I needed fuel to add to the filter cup in event that I do run the filter dry (and not wanting to try syphoning fuel into a container to transfer to the fuel filter/separator cup which could get messy).

Anyone been there and done that?

[OverEasy]

Hi 45Plus!

Most water separating fuel filters have a hydrophobic membrane in the filter construction that precludes water from getting through the filter. I’d suggest looking at you particular filter and manufacturers information to confirm this for your particular filter.

Best Regards,
Over Easy

[45Plus+]

A wise idea....that I am often guilty of overlooking. I don't think any paperwork came with the filter/separator (RACOR) but I will see what I can find on line.

Of course, the best thing to do is not let tank no. 1 run dry. I can sorta see the level of fuel show up through the red plastic and I can also slip a toe under the tank to get a sense of weight (I am running with just a 6 gallon tank on each side so there's room to get my foot in there. I am thinking about the idea of putting a hatch in the fuel cubby seat but since there is a cushion to be lifted, perhaps its just as easy to lift the cover with it when checking the fuel gauge. I can definitely see the advantage of a small hatch for refueling the larger 12 gallon tank (I still have one that I can use for longer trips - ie 12 gallon tank on one side, two 6 gallon tanks on the other. I like the idea mentioned above about using the fuel filter/separator as a "Y" so at least two tanks can be connected to the engine (with shut off valves or not).

[Russ]

A late entry to the discussion and a couple of questions to add to the topic.

My fuel filter/water separator (an R12T) is lower than my gas tanks and my primer bulb is between the tanks and engine. The instructions that came with my filter said to fill the lower cup of the assembly with fuel then screw it onto the base. That worked just fine and the engine started even though there was no fuel in the fuel lines (all newly installed) - apart from what might have been forced into them by the primer bulb.

This whole discussion got me thinking about what would happen if I inadvertently allowed the engine to suck a tank dry. Would it draw in all the fuel in the lines and the filter/separator? If so, hopefully it would not pull whatever water that happened to have accumulated in the filter into the engine (?). And, to prime the fuel line/filter system when I connect up fuel tank no. 2, would I have to add fuel directly to the filter/separator cup again to get fuel to flow? I've been carrying an expensive 1 litre can of gasoline in the boat just in case I needed fuel to add to the filter cup in event that I do run the filter dry (and not wanting to try syphoning fuel into a container to transfer to the fuel filter/separator cup which could get messy).

Anyone been there and done that?

I have 2 tanks and ran one dry last week. Never did that before. I was on the water and didn't look at the filter/separator to see what was going on there. I just switched tanks and pumped the bulb, restarted and went on my way.

Good question: Does it suck water from the bottom of the filter? For some reason, my memory wants to say there was fuel left in the bowl of the Raycor filter when it ran the tank dry.

I could research this, but I bet the filter draws fuel from the TOP of the bowl and when it ingests air, it feeds the line air.

I drained all the fuel/water at the end of last season and the filter was dry as a bone over the winter. I didn't refill the filter and install it. That would not be very easy. It just filled on its own. I think squeezing the bulb was sufficient.

[45Plus+]

Thanks - that's good to know. Next spring I will see if the primer ball can fill the filter/separator before bothering trying to take it apart and fill it.