Polishing filter upstream of mechanical fuel pump?

[scratchee]

"Replace the o-ring?"

[Dave Neptune]

That's the o-ring on the filler cap!

Dave Neptune

[joe_db]

My water issue was solved with a new O ring
Note that ethanol corrodes the metals in our cabs and water, even water you can't see in suspension with the ethanol, makes it much worse. I got ahead of this issue by getting a new carb, a new O-ring, and adding SeaFoam to the gas every fill. SeaFoam is cheap and has decent anti-corrosive properties. I think once the carb gets eaten into beyond a certain point, it will keep corroding. It may not be there yet for you, but the water HAS to be kept out from now on. I actually have heard good things about those old Perko filters, they are easy to drain and easy to clean. The Moyer polisher will catch anything that gets past it.

[scratchee]

Yeah, I've kept an eye on the o-ring on my filler cap. I've always been a little nervous about the filling port being essentially on the bottom of a bathtub if my cockpit drains get clogged (most likely with leaves while on the hard). The o-ring seems to be in good shape, but I've never replaced it.

When I think about water in the fuel, I assume there are two dangers: fuel that won't burn, and/or corrosion that puts sediment in the fuel stream. I think my problem, if indeed it is caused by water, is the latter. My symptoms are the engine not starting after it has sat for several days. It will crank and crank and crank, and when the battery is about dead it will finally fire weakly for a turn or two. If I'm lucky enough to get it started before the battery goes dead, I can nurse the throttle and choke for a couple minutes until she's warm. After that, it runs fine for as long as I need. So if I had actual water in my fuel line, I would think there would be enough good fuel in the carb and pump to get me started the next time.

[scratchee]

My water issue was solved with a new O ring....

What issues were you having?

Note that ethanol corrodes the metals in our cabs and water, even water you can't see in suspension with the ethanol, makes it much worse.

Thanks, this addresses my original question, because I figure that if the carb is effected the mechanical pump probably is too. Last week I removed the sediment bowl in the newly-overhauled pump, and it was already covered with a fine powdery coat. Nothing that would interfere with the engine, I don't think, but certainly an indication that something is getting added to the fuel. So putting the polishing filter after the pump is probably what I'll do. And I'm going to look at discarding the existing fuel in the tank, as well as a possible tank replacement, or at least an internal inspection. I have a cheapy inspection camera that I may be able to use without blowing myself up.

[ndutton]

The o-ring seems to be in good shape, but I've never replaced it.

How long have you owned your boat?

[Dave Neptune]

Residue

If you are getting residue in the freshly rebuilt carb and pump you have bad fuel. The powdery stuff you see is from condensation attacking the body of the carb. No amount of filters will filter it out as it is emulsified into the fuel as a liquid. This liquid flows through the filters freely and shows once the fuel begins to evaporate.
I see a few things in your posts that need clarification.

Hard to start can also be from a weak battery not spinning the beastie fast enough. Have the battery tested and check the connections.

The choke may not be all the way closed check it visually. OR a vacuum leak at the carb base.

Have you checked for a good spark?

Did you prime the carb with the bail on the pump?

Next thing is fuel. This is a lot of fuss for something so easily checked out. Get a small gas can with fresh regular grade gas and hook it to the carb and gravity feed or to the pump and let it feed the carb. If it starts and runs don't use the fuel in the boats tank!!!

Dave Neptune

[ALMA]

Original 1977 FRAM gas/water separator

I've had one of these on my Pearson since new. It is steel and aluminum cap. It has been dependable. I have never had a problem with water in fuel or phase separation. It would take a lot of water to saturate today's 10% ethanol fuel- remember "Dry Gas" was simply a dose of ethanol alcohol to absorb water in fuel system to prevent icing. The Pearson has a MONEL tank which is a real premium material for gasoline tanks. My inlet is also in the cockpit sole and has the original chrome plated bronze inlet. I do not use an O-Ring but I keep the threads in the cap heavily greased. Standing water for days or weeks over the gas inlet may overcome any effort to keep the gasoline 'dry'.

[Dave Neptune]

Filter water separaator

Fuel/water separators work very well at letting the "WATER SETTLE" to the bottom of the filter for extraction/storage. They are for filtering particulate matter down to there micron rating and do a very good job. They will not filter out "emulsified water or goo" as they just pass on through. It is bad fuel and then it gets to the fuel system and in the carb. When the fuel evaporates away the emulsified water or goo precipitates out to deposit and cause havoc to the carb body and orifices.

No matter how many filters you add bad fuel is bad fuel and the "bad" won't filter out unless it is a particulate!

Dave Neptune

[scratchee]

Next thing is fuel. This is a lot of fuss for something so easily checked out.

No worries Dave, the carb and fuel pump rebuilds were due just on general principle, and they were fun winter projects. How else would I have ended up with this beauty hidden behind the lower drawer in my saloon?



The two barbs are where I'll be putting that polishing filter.

Your other helpful tips I've either already done or have reason to believe they're not an issue at the moment (battery, spark, etc). I do expect to discard the fuel in the tank. Thanks!

[capnward]

For many years, I have had two "polishing filters" after the Racor: one before the mechanical pump, and one after. I tend to replace them yearly (NAPA 3012 or 3032), or if I clean the carb passages. They are about $6 each. The mechanical pump seems to be able to handle the added restriction of flow of a second filter. Sometimes I blow through the old filters to compare with the new ones, and the old ones are harder to blow through. This may not mean anything, just that the old filter elements are wet.
I also installed a valve on the bottom of the RACOR bowl to drain any water out. I there is any, I replace the Racor as well, assuming it has loaded up with water and cannot separate it out of the fuel anymore.
If you only have one polishing filter, it should be after the pump. That way any particulates in the pump will be stopped, theoretically. I think the chalky white residue is water corroding the aluminum. Put MMO in your gas if you aren't already. I think it will help the corrosion. I suspect the water in your tank may be getting past the fuel fill caps, then attaching to the ethanol. Then the ethanol/water mixture gets past the water separator. I stopped getting the emulsified goo in the RACOR bowl and in the carb when I stopped using ethanol gas. In my anecdote-informed opinion.
I see you painted your carburetor and mechanical pump gold. I feel the same way about mine. Happy sailing!