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Houseboat Fuel Problems - ethanol gas, water condensation, and gummy carburetors

by Russell
(N Fort Myers, Fl)

The houseboat runs great on external fuel, but not on fuel tanks.

The houseboat runs great on external fuel, but not on fuel tanks.

We're trying to troubleshoot houseboat fuel problems, and there's water condensation, ethanol gas, and gummy carburetors that are causing an ongoing persistent fuel problem.

We have a 57 foot Carri Craft houseboat and we carry about 400 gallons of fuel and another 100 for the generator. The tanks are stainless and in good shape. There are 4 fuel filter/water separators on each side.

Two of the filters in the tank room, and another two filters in the engine room BEFORE the inline filter and the ceramic one inside the carburetors. It seems to me that this should be more than sufficient to stop anything in the fuel system that does not belong. Wrong answer!

I constantly have water and a sticky heavy substance gumming up the carburetors. I have rebuilt the carbs last week and restarted the engines on a 6 gallon fuel can. They run beautifully. On a hunch I disconnected the fuel supply at the carbs and run a line into a jug to see what was in the lines.

The fuel deposited in the jug was the nastiest fuel I have ever seen in over 50 years of working on boats. There was so much water and sediment that I could not believe it.

These tanks were supposed to have been cleaned out about 6 months ago and had fresh fuel added. It seems that if the fuel sets for any length of time; 6 months or there about, the fuel seems to create its own water. I think condensation is a possibility but why so much?

Someone told me that these new fuels that contain ethanol tend to condensate more water than gas that does not contain ethanol. Does anyone know if this is true? One guy at our marina said that the fuel that has an even higher amount of additives can get real nasty in a very short time.

I never thought about the fuel having an organic based additive (corn) could do such a thing. This person said that some stations even went up to and beyond the 10% posted on the pumps because it was a way to save a few dollars more on the fuel cost.

Like a lot of other boaters I have gone to the local gas station and gotten a couple of 5 gallon gas cans loaded to carry home with me.
This saves a lot of those high dollar side-ups at the marina pump.

For some reason the marine fuel with the supposed "no road tax" fuel costs way more than regular fuel at the pump. If the road use taxes have been lifted the fuel should cost less, not more.

If anyone is looking to ask me questions about the shelf life of fuel don't bother. I have no idea.

Water leak into tank? Not likely, there are three tanks and the same problem rears it's head in all of them.

The only thing common to all the tanks seems to be the fuel. The engines are well taken care of and in good condition.

I was just wondering if I am alone on this or not.

Any clues, Russell in N. Fort Myers, FL

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Reply - Answer

Well Russell, sorry to hear about your fuel problems. You are not alone as my neighbor is suffering from the same situation, and his boat also came from Florida.

He had the carbs totally rebuilt as they had enormous amounts of crud, sediment, and a gelatin gummy substance blocking all the orifices. His carbs were dripping fuel and overflowing, instead of vaporizing the fuel.

We have pumped the bottom of his tanks, and they appear to have a rust colored, water gummy substance on the bottom. As always, his fuel tanks are not easily accessible. Once he rebuilt the carbs, he ran the engines on two external 5 gallon tanks of fresh fuel, and they ran like new.

Now the big questions is, is this scenario coming from ethanol based fuel, or is it a storage preservative issue?

Lastly, hopefully some of our readers will share and post comments about their houseboat fuel problems, tips, and experiences. Feel free to use the "Click here to post comments." link found near the bottom of this page.

Thanks again for sharing, IAN from all-about-houseboats

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Comments for Houseboat Fuel Problems - ethanol gas, water condensation, and gummy carburetors

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Want to clean out 100 gallon tank
by: Anonymous

Anyone have a good method for removing the brown gel substance from the bottom of the tanks when this issue happens?

Ethanol fuel
by: Anonymous

I had same issue, health problems kept me from using my boat and ethanol seems to turn to water. I changed filters and added sea-foam in my fuel tanks, it made a world of difference.
I never had much faith with additives etc... but Seafoam does wonders.

Houseboat fuel problems
by: Anonymous

My houseboat is on Lake Oroville, in California and the last 6 months I have had nothing but trouble, after having none at all in the previous 14 years.

I admittedly buy gas at a station and haul it in to save 1.50 a gallon, but since having to pump the tank twice recently, I am deciding something has to be done.

I ask at the Marina (it was a weekend, so no one around knew anything,) but they couldn't tell me if their gas had ethanol or not. If it didn't, I would suck problem continues.

One post says keep the tank full to avoid condensation (my tank is 300 gallons), and if it then goes bad, I am out a it up and start buying gas there. Otherwise, my small fortune.

Other posts say to only buy as much as you can use in a couple of months (if full, my tank would last ages). So a dilemma as to which way to go.

For now, I guess I will just start using Sta-bil marine and see how it goes. Any other advice would be appreciated.

Thanks for any replies.

Solving condensation problems
by: Chaz

If you fill your tank completely full when you store it, then you will not have any more condensation problems.

The water vapor will drop out of the air into your fuel when the temperature of the air in the tank drops in temperature.

If your tank is full, then there is no air for the water to drop out of. Research relative humidity.

Obviously stabalizer helps hold the actual gas together but do not know why.

by: John

I had nothing but problems with my Mercruiser I/O
when I was using the ethanol in my 100 gal tank on my 52' Sunseeker Houseboat.

I took the carb off and it was all gummed up. I rebuilt it and a few months later the engine was hard starting and ran rough. I sucked it up and spent $600 for a new carb and now I only use a 6 gallon tank that I keep fresh gas in.

Ethanol stinks. The only reason that our cars tolerate it is because the gas doesn't typically sit for very long between fill-ups like it does on a houseboat.


Marine fuel
by: Anonymous

The fuel your are getting from the Marina may be where you are getting contaminated fuel. You need to ask how long the fuel has been in the storage tanks and when did they get fresh gas.

Have you tried using stabil fuel additive in your tanks? This helps keep it fresh also.

Ethanol Houseboat Fuel - wet fuel or aviation gas
by: Wet Florida

When it comes to ethanol and houseboat fuel, I had to have the fuel pumps and injectors on my 60 Merc OB and 150 Yamaha OB on two other boats cleaned and/or repaired (over $1,000) for water gumminess.

Warranties don't cover it, so I figured I better figure something out before the Merc 135 on my pontoon houseboat went bad. My mechanic (30+ years) and friend, and a second marina owner in my Rotary Club, separately suggested aviation gas.

Air-boaters in Central Florida use it and it's 100 octane and NO LOUSY ETHANOL. I let my fuel sit up to 6 months now without issue. They also suggested non-ethanol gas, which some marinas sell here. Both are about $1.25 more per gallon than regular unleaded.

I have not had any problems in more than 2 years. I also use marine Stabil for cleaning. It also seems as though the fuel lasts longer, or that I get more run time from a tankfull (more to burn than energy inefficient ethanol, I guess). Good luck with your gas....

Fuel problems
by: Anonymous

Are you sure the problem is from the ethanol fuel. I had a similar problem on my 43ft Nautaline and found that the gas fill caps were not sealing and allowing water to enter the tanks. Also check the position of your fuel tank vents they can also allow water to enter.

Seafoam is great in houseboat gas tanks.
by: uppermiss

Ya, SeaFoam works great for houseboats!

ethanol blend problems on houseboats
by: Bill

Minimal amounts of water will draw ethanol out of blend away from gasoline.

cheap fuel
by: Dan Pedersen

I've got two cars, an old one with carburetor and a newer one with fuel injection. The one with fuel injection has never any problems, but the old one can't use cheap gas. Probably because of low quality fuels.

The discount companies by leftovers and contaminate fuel and add alcohol so it can be used in modern motors. But not in my old 1984 VW Polo. As a consequence, the old car runs on high quality fuel, and the newer one on cheap junk.

The idea of methanol absorbing moisture sounds right. But my VW Polo doesn't like cheap fuel. Not even fresh from tap. But then again. How fresh is cheap fuel.

ethanol fuel...
by: River Rebel

Well you all, I live up here in Iowa right on the Mississippi. I run a 36' Gibson houseboat with twin Ford V-8's, have had her for 5 years and I run ethanol fuel alway's.

I have never had a issue with water, gummy or slime in my carbs. I typically take it off the river in late october or early november and usually 15- 20 gallons left, next spring I top off each tank with fresh batch of ethanol fuel.

Have never had any problems or issues. Maybe our ethanol in Iowa is a better grade.......

fuel problems
by: Uppermiss1

I have had similar problems in Wisconsin. Since I started using SeaFoam (one ounce per gallon) I have had no problems. In fact, I now use it year round in all my engines, chain saw, tractor, lawn mower, etc.

When I store the boat for the winter there is often a significant amount of gas left in the tank. It still works fine the next spring.

Ethanol Fuel Issues on Houseboats
by: Mark, South Australia

I contacted a number of petrol companies on behalf of our boat club and they cautioned against using fuels containing ethanol in boats. Its use in light aircraft is banned by law here.

The ethanol is hydroscopic and permanently changes state when it picks up moisture. When the atmosphere becomes condensing due to temperature drops with high humidity, problems are increased.

The problem gets worse when there is a large surface area of fuel in contact with the atmosphere. Fuel also breaks down faster with atmospheric contact.

According to the fuel companies, our standard petrol (91 octane) will last 12 months if stored out of contact with the atmosphere. I always leave my fuel tank full to reduce the contact the fuel has with the atmosphere for these reasons.

While I don't leave ethanol fuel in my tank when I'm not living on-board, I often use it when I'm on an extended voyage without any problems at all.

Towards the end of the trip I change back to standard petrol so the ethanol get used up before we get back.

Reply - Answer
Well Mark, I wanted to thank you for sharing some great info on ethanol based fuels. I see that we have to used ethanol based fuels quickly, and not leave it stored in our tanks.

IAN from

Fuel & Ethanol in Houseboats
by: Old Houseboater

Ethanol containing fuel is the mechanics best friend. Since the advent of this fuel and the problems it causes in boats, it has become a significantly big part of service income for most marinas.

Don't put any more fuel in than you can use in a month.

Fuel problems in houseboats
by: Bill in Florida

I had the same problem when I had my boat in the south end of the state. When I got back home 2 years later, and used the fuel at my home marina, i had no problems.

Yes ethanol can cause some problems, but think, it is used as a fuel additive to disperse water, as in Heet and other alcohol based products. When I added it to the fuel, nothing happened.

After having all the boat owners sign a petition, the tanks at the marina were found to have sea water in them. That will cause a major sticky contamination.

Storms, erosion of the tanks, etc. will cause havoc with boat fuel, gas and diesel. Using fuel stabilizers helps greatly.

Ethanol fuel on houseboats.
by: roger

Been through the same problems and it is all about the fuel. There are lots of websites dealing with it. Ethanol starts separating the day you buy it, but there are some good additives that work well, just don't try to keep fuel more than couple months.

We here in Florida are probably in worst place for ethanol enhanced fuel. Fuel prices in marinas can be high, but look at the insurance for spillage, and it will scare you.

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