Carb Overflows

[ndutton]

The bigger question is where did the water come from that created the rust? Pure gasoline doesn't cause rust.

[Al Schober]

Neil,
That though crossed my mind too, but I think these alcohol fuels may entrain enough water to cause what I see. Not enough water to separate and settle out, but enough to cause corrosion of a filter with steel parts.
I'm still pondering why the rusticles are around the outside of the filter cap but not in the center.
Might be time to get my 6' copper tube and probe the gas tank again...

[ndutton]

I don't necessarily buy into the ethanol doomsday stories but my mind is not closed on the subject either. If you can positively connect that rust to ethanol, I'm listening. I'll offer this: the last three automotive in-tank fuel pumps I replaced all had steel parts/brackets,fasteners etc. and there wasn't a lick of rust anywhere. FYI, our local weather has a strong marine influence (only a few miles from the ocean) so I'm equating my cars and boat environmentally, at least darn close.

[BunnyPlanet169]

If your fuel use is similar between vehicles, I would agree. I'm guessing for most of us the difference between cars and boats is the duration that fuel is in the tank, and the substantially higher fuel use and mixing in cars. IIRC, the EPA also now mandates vapor recovery, which will limit tank breathing also. I use 15 gals a week in my car with two fills and fresh fuel, and maybe 30 in a summer of boating with maybe 2 fills and a lot of sitting, breathing, and absorbing water vapor.

Practical Sailor did a nice article on using home built desiccant filters in the tank vent line, with some convincing corrosion test results. I think we can live in the ethanol world, but need to rethink plain air tank venting because of the long residence time in the tank.

[ndutton]

My go-to question on things like Al's rusty filter is why his and not mine? If as suggested the contributing factors are:

• ethanol, I have that
• low fuel usage and therefore long storage, I have that
• open vented fuel system in a marine environment, I have that
• engine problems, I don't have that
• fuel that looks like root beer, don't have that
• rusticles migrating about the fuel system, judging by my regular carburetor clean-ups/rebuilds, don't have that either.

So the question remains, why Al's and not mine? Something is different with his fuel system than with mine. It's my opinion the possibility of contamination has been discounted too quickly in favor of the popular scapegoat, ethanol.

Note:
Substitute any of several good running A-4's represented on this forum with "mine."

[zellerj]

filter is paper, and paper can trap water - just like Bounty

It appears to me that the filter is paper, and paper will attract water. It will hold on to water and let fuel pass. So I bet the fuel passing through the filter had a bunch of water in it - so much so that it would lead to poor performance, but was trapped in the filter paper and over time rust formed which caused further issue with the carb.

I am not a big fan of water separators fuel filters, but I am a big fan of checking the gas tank for water. This can be done with a paste that turns red when water is present in the gas. The fuel tank is a big water separator, so big that it takes a few years or so for enough water to get in the tank to cause issues with water making it to the carb. Check for water once a year, have good o rings on the fuel fill cap, and buy gas at places that have a good turnover, and one should not need water filtration in line to the carb.

Best,
Jim

[edwardc]

When was that polishing filter last replaced? I consider all filters an annual replacement maintenance item. I do mine each spring.

[Al Schober]

Did a bit more with the saw this morning - wanted to see the outlet side of things. Found rusticles on the inside of the element cap, on the metal clip used to form the element into a circle, and on the inside of the outlet tube. Next stop for all this stuff is the carburetor!

[swallace11]

Thanks for sharing your polishing filter disection Al. How old was the filter?

I recently did mine after 5 seasons and about 100hrs of use. After cutting the pleated paper filter out and drying it, I found the upsteam side to have gray cast with a few light black spots, so I assume its traping small hose particles, ie making a contribution to clean fuel to the carb. The carb(downstream) side of paper filter was bright tan-orange.

Surprised at the amount of corrosion you experience in metal filter casing and blankoff. I cleaned out my mechanical filter sediment bowl for the first time in about 10 years and found quit a bit of corrosion at the bottom, though the filter screen was clear--know now to be more diligent. This is despite the fact than I do an annual cleaning of my tank bottom with a copper tube also, typically getting some rust particles, maybe some water droplets, and a gallon or so of somewhat milky fuel(water containiing) which I throw away.

[JOHN COOKSON]

I'm going to rethink using a polishing filter unless I can find one that passes the magnet test.

Al

You could temporally use an "illegal" clear in line plastic in line filter until you get this sorted out.
It would let you see what is going on inside the filter and pass the "magnet test".

TRUE GRIT

[Dave Neptune]

The filter was so old I believe it was rusting out from the inside. Seen that before. The rust builds up expands and blows the element.

There is water in the fuel and or tank or the filter would still look good albeit "older". The inside of the filter is a good clue.

Dave Neptune

[joe_db]

When I use the cheapie filters I *always* replace them yearly. I can afford the $10 or so and I have had them rust through from the inside out AND the outside in . They are DESIGNED to trap water after all.

[Administrator]

When I use the cheapie filters I *always* replace them yearly. I can afford the $10 or so and I have had them rust through from the inside out AND the outside in . They are DESIGNED to trap water after all.

Hmmm. I always figured they simply trapped solids and would not preferentially hold water versus gasoline.

I wonder what explains how those oil-absorbent rags work.

My Honda outboard has a little transparent plastic section in the fuel line, a bit larger than a pill bottle, with a red plastic ring inside. If that ring is floating, it's floating in water. In gasoline, it sits on the bottom. It's just a warning device. Doesn't filter or separate anything.

Bill

[ndutton]

(Re: polishing filter) They are DESIGNED to trap water after all.

I'm having a problem with that too. The polishing filter is a strainer for particulates. A water separator uses gravity to stratify the water out of the fuel and therefore has the requirement of orientation. A water separating filter has both.

A water separator utilizes the difference in weight (actually density) between water and fuel. The separator has a reservoir wherein any water in the mix settles to the bottom. The fuel is then drawn off the top for delivery to the engine. Because it functions this way it must be mounted so the reservoir is on the bottom. That is, there is a top and a bottom and the mounting is critical for proper function. Not so with a particulate (read: polishing) filter.

[Dave Neptune]

Normal

Gentlemen, the water can "gather" and sit in a low spot just like air can be trapped in a "high" spot. Unless the flow is really moving which it wouldn't be much a gallon an hour the air and water can just sit where they are!!!!!

How often do we hear, "there is an air bubble in my CLEAR filter does it hurt anything?".

I have seen many of the steel canister type of filter literally rust through at a "LOW" spot.

Dave Neptune