Water and fuel don't Mix

[John S]

We just cut short a 5 day trip and hauled the boat out of the water and back home because of water in the fuel.

The problem started almost immediately after start up when we launched, it only showed as poor idling on my Port side Honda BF90. It was shaking and idling around 600 RPM. Idling out of the harbor I felt the spark plugs and found a cold one and changed it. Bottom cylinder by the way. Then I looked at the Racor, didn't look unusual, but I drained it anyway and nothing but water was coming out. Not sure how much but at least the entire plastic area on the bottom was full of it. I then started draining all the carb float bowls. Still idling out of the harbor, no improvement. We hoped all would be well once we got under way. Motor developed full power and run well at high RPM, but had hell idling. At another port I pulled and drained the Honda inline filter and checked the fuel pumps. No glass jar so not sure about water in that filter.

Three days into the trip I decided I better get it home and find the problem. It was all water. The Racor had another HUGE slug of water filling the bottom. The filter on the motor when drained into a glass jar was half full of water. I ran and drained carbs on and on and finally it started running right. Can't believe that Honda ran fine at full power before all the water was removed. I've never had a water problem before and we already have over 100 hours on the motors in the last two months. Only the port side is affected.

QUESTIONS:

WHERE IS THIS water COMING FROM??
My gas comes from HIGH volume dealers, is that still the most likely source?
If the water came from a gas station would it make it to my motor almost immediately on start up? In other words is the last fill up the one most likely to blame?
I checked the O-ring on my gas cap, looks great, anywhere else I need to inspect?
I know there is still more water rolling around in the bottom of that tank, any suggestions for its removal???
I've replaced the Honda Inline filter, should I replace the Racor filter right now too?
Has anyone been in a C-Dory tank and know if the pickup is right on the very bottom? I know I have about 3 gallons of unusable fuel in each of my boat tanks according to the manual. Could that 3 gallons in the bottom be nothing but water now??? Ouch!
New problem to me, I would appreciate any advice on the subject.

Thanks

[dredger]

If your fuel has ethanol added to it like it does here in Md. If you don't keep your tanks full the ethanol attracts moisture through the tank vent which ends up as water on the bottom. We have used a product called Star- Tron that prevents the water from seperating.

[drjohn71a]

I'd try to dispose of all of whatever is in the bottom of the tank, install new filters. Can you get a siphon hose to the tank bottom? Is there an inspection plate? You may have to get under the cockpit deck to clean it all out. Some ppl on here know alot about the TomCat 24s and they should chime in soon to help you out a bit.

Half full tanks can actually "rain" inside the tank whether there is ethanol in it or not. While there are probably better ways to get the moisture out, I have used HEET (I think Isopropyl Alcohol) to try to suspend the moisture and burn it off of whatever you cannot siphon out. Good also to use fuel stabilizer all the time and keep tanks full all the time, to my thoughts. I understand some modern advisors are saying that empty tanks have less of the ethanol to cause water problems, but up there in the PNW, I think the risk of "rain inside " the tank is very high on empty tanks.

John

[thataway]

Startron (Soltron) is an enzymatic fuel conditioner. It claims to "breaks down this excess water and sludge to sub-micron size allowing it to be safely burned away during normal engine operation."

Our experience over about 10 years with this product is that it tends to help with algae/gums and similar problems. I would not relie on it to get rid of large amounts of water.

I tend to think that probably the water is related to condensation --not sure if you have the plastic or aluminum tanks.

I would remove the fuel guage plates and use a drawltube to suck out any water on the water (remote pump, with a water separator/filter) and put that fuel into separate plastic tanks. You can do the same thing by raising the bow of the boat, and then drawing from the fuel pickup, filter/water separate, by "polishing" the fuel.

[Brock]

Not sure if you could be having the same problem I had last summer with my 2006 255 TC.

I was taking on huge amounts of water (up to a gallon) in heavy rains in both tanks, most in the port. I eventually replaced the tank vents with a Perko brand vent that has a little hood to shed water away from the hole. I have had no issue with water since. Not a sign of water in the separators.

In my TC, the water would get sucked into the separators (and begin to overwhelm them) as the boat went up on plane, so the water was obviously sitting forward in the tanks when the boat is level in the water.

The fact that just one of your tanks seems to be affected could indicate that it is coming in one of the vents. On my TC the vents are located right below the gunnel drain "gutter" so water poors down onto the vents in heavy rains. I concluded (I could be wrong) that more water entered my port tank because of the starboard list of the 255 TC.

I don't know of anyone else having this problem but I think the factory moved the location of the vents on later boats. I hope you figure it out. I know what a pain it is to deal with.

Brock

[flapbreaker]

It's very unlikely that THAT much water is from condensation or filling up at the station. I only hear people with boats getting water in their tanks from gas stations. If it were as common as some boaters think then one would think that you would hear a lot more complaints from motorists.

Anyhow it most likely got in there through the vent hole or someone accidently started filling the tank with water thinking it was the holding tank???

Did anyone wash the boat and use a little too much water near the vent holes? Were there any recent rough water trips? Just thinking here.

[drjohn71a]

I had an old houseboat with twin aluminum tanks that continually condensed water... I don't think the vents were a problem with it... I know you can get a great deal of water in there just from condensation. Remember, it condenses just about every morning, so is relentless.

The TomCats have had some problems with water from vents, I hear, but so far mine has done OK.


Keep hunting and you'll find the problem(s),

John

[drjohn71a]

John,

Another thought on all this. I guess you are familiar with the common story where a couple buys a new trawler that has run faithfully around the local bays for years without problems. They do test runs on nice days and the boat's performance seems bulletproof.

Soooo, they load up and take off on a two week cruise through open water. Guess what? Tons of engine problems - fuel problems. All the debris and water in the bottom of the tanks that had accumulated over the years of calm water use got stirred up and entered the engine's fuel system.

I think this could be a big part of your problem. As such, I think you'll be able to get a handle on it soon and the boat, with proper preventive measures should become dependable for you.


Have fun out there,

John

[Sea Wolf]

This is just a thought about ways to find a solution to this much talked about condensation problem:

The root of the problem is the air being exchanged daily from the heating/cooling cycle and condensation on the inner walls of the tanks, especially aluminum because of it's greater heat conductivity.

Why not use a bladder type tank to eliminate most of the air inside the tank? This would eliminate most or even all of the exchangable problematic air space.

I don't know how hard to install, or expensive, or practical the bladder type tanks would be for a boat, but it might be an answer.

It's my understanding that fuel bladders are used on airplanes routinely.

Just a thought!

Joe.

[John S]

Thanks for all the input guys, here's some more info.

My tanks are aluminum.

We've been running the boat all summer in often rough pounding conditions.

Recently we were anchored while fishing in 5 ft sea and the tide had us in the trough for a while, although the angle of the boat never got scary we did actually take a couple waves over the side rail in the cockpit. These would have also hit the side of the boat and could have provided some water to the vent.

It is a VERY uncommon for me to not refill my tanks to the top when we get back from a trip.

I'm VERY interested in a better vent design. I will try and post a photo of mine with its location today.

I'm the only one who services the water on the boat, which is only about 1 foot away from the fuel inlet. I'm confident I didn't stick the water hose in the fuel tank. If I had there would be 5-10 gallons of water in the tank and I don't think the engine would have ever run at all.

I would like to siphon some fuel out of the bottom of the tank, BUT I can't ever find a piece of hose straight enough to go right to the bottom. Any thoughts???

One more thought, my boat always runs with a slight port list, because of the water tank and waste tank on that side and the fact that every other person, other than myself driving the boat, is usually seated on the port side. I attempt some load balancing but its not always enough.

[John S]

Here's the photos I got of the vent.

Brock does this resemble your offending fuel vent??

I also noticed that my fuel pickup is in the center of the tank and not in the back end.

[thataway]

Yes, it is certainly possiable that you got water in your tanks thru vents. I did this with large diesel tanks once, in heavy weather. We had to completely drain the tanks, and get in and clean the bottom out.

Some Tom Cat 24's have had the tank replaced, so by cutting an access hole, it would be possiable to get to the sender (I have access holes in my TC 255).

Yes, I have seen situations where this much water got in with marina fuel. It is very rare in auto service stations, but happens more often with marina fuel stations. This is probably because of condensation. The better marinas, will have water separators and fuel filters on their lines to the pump.

[BrentB]

To turn water to gasoline, you need a gasoline pill.
see http://en.wikipedia.org/wiki/Gasoline_pill

[BrentB]

from
http://www.yachtsurvey.com/myth_of_condensation_in_fuel_tanks.htm


Leaking Fill Caps

By far the most common cause of contaminated boat tanks are deck fill caps that leak. Most of these things are stupidly mounted flat on decks which may puddle with water. The cap has a tiny little O-ring that is supposed to seal and keep water out. DOES IT? I wouldn't depend on one of these things unless I could prove that it doesn't leak. Check the condition of the o-ring and weather it is sealing.

One way to check positively is to clean the o-ring seat thoroughly; next apply some black or any color paint to the o-ring and screw the cap in place, tight. Then remove it and see if the paint has been completely transferred to the ring seat. If not, you now know where the problem is.

Another problem is the simple failure to seat the cap fully after refueling. This actually happens a lot, so check to see if the cap is loose.

The Tank Vent

Improperly located fuel tank vent fittings are one of the top causes of water getting into tanks. When this is the cause, if you are a salt water boater, then it will be salt water in your tank. A fuel tank vent fitting on the side of the hull should be angled down and aftward. If angled in any other direction, you've got a problem that needs fixing. Watch out for deteriorated plastic and zinc alloy fittings; some of these things deteriorate incredibly fast.

The vent line should have a riser loop on the inside. That is, it travels upward first, then downward. If not, that is another potential problem.

Check the Fuel Gauge Sender

One final possibility is the fuel gauge sender plate on top of the fuel tank. These are often made of steel or have steel screws that can rust away, a situation I've seen several times. Is water puddling on the tank top? Test all screws with a screw driver to make sure they are securely seated.

[oldgrowth]

John – I hope it is not because of the fuel vents. I just installed two on my boat that are like yours. I also have aluminum fuel tanks. However, one advantage I will have is, I placed the vents higher up than yours, they are on the side of my cabin and I have a drain for my fuel tanks so I can easily drain them if necessary.
________
Dave