Water in Fuel

[Sahara53]

Folks I have experienced water in the fuel tank for the second time last month, very frustrating, unexplainable. Following retrieval we towed back to dealer (4hrs @ 38 degrees) who sucked out over half a litre of water sitting on bottom of underfloor tank. The tank is the Bermuda 120L plastic job sitting under the floor.
Seems no possible explanation, some question over the filler point although this has been eliminated as cause. Now suggested that the cause is condensation.
This problem initially occured last Easter and we had tank removed and air dried, Yam115/2 stripped down, fuel lines all cleaned, new fuel filter w/water bowl. Boat then sat until 5 weeks ago with half fuel and kept in large farm shed for all but 3 weeks, during this time heavy plastic covered the fill point to stop any water entering this point.
We filled the tank and launched after preparation and lasted about 700m before Yam said enough. Investigation found filter bowl full of water. Dealer/builder can't explain, all fellow boaties can't explain, Being SA and having busy family life, the boat does unfortunately get lots of time to be lonely during the off season.
Does anyone have any clues?

[Grand_Marlin]

Yep, condensation.

Always keep your tank full of fuel - always... this stops (or at least dramatically slows) the condensation process when the boat is stored.

It is amazing the amount of water that can condensate in a half full tank.

Plastic tanks seem to be the worst... dont know exactly why.... but aluminium / stainless tanks seem to give less problems for underfloor tanks.

I use and swear by CAV water separating fuel filters. Have never had water go through them.

I have had water go through the more expensive Racor filters on two different boats.


Cheers

Pete

[Sahara53]

Thanks Pete this seems to be the common response whoever I askthe easiest way of controlling the situation. Does this not create a problem with stale fuel?I still am confused as to why others don't have similar problems, it seems many boats are now fitted with these fuel tanks.

[Grand_Marlin]

It would depend on each boats circumstances.

In a nutshell, the hotter the tank can get, with the least amount of fuel, the more it will condensate...

What brand of filter are you running?

Stale fuel is an age old debate.

It obviously can happen, but personally I havent experienced it.

It is the fuel / oil mixes that go off quick, but I imagine your motor is oil injected.

If you want to know any more about condensation, ask anyone from Queensland... the humidity up here makes it a big problem.

Get the water out of your tank, fill it up full and the problem should disappear.

Cheers

Pete

[2DKnBJ]

Another thing you can do is put a cup of metho in the tank.This helps the water burn if it gets past the filter and into the motor.I have been doing this for abuot 20yrs and have not had a prob with water yet.
Cheers Dazza

[Grand_Marlin]

Good idea too Dazza,

Just try and get as much water out as possible first, otherwise it will create more problems in the carby if too much water goes through.

[sf17fisherman]

yeh both the above are very corect
after use fill the tank right up and add some metho (althought not needed all the time only if your going to let it sit)
if you haven't used it for such a long time i would surgest taking it for a good run on a family day up river somewhere and use atleast 1/2 the tank then top back up with fresh and that should do the trick
apart from that maybe pump half out and use for backburning or something

many say use it in your car but i say if your not going to use it in your boat motor then why would you in your cars

[billfisher]

Well it seems like too much water for condensation. I leave my tank half full months and have no trouble controlling condensation by draining the filter occasionally. I live in Sydney too and it is quite humid in the summer.
Is you tank large? Mines only 70L.
In any case I'd be wary about leaving your tank full for months. Stale fuel can destroy your engine. I would use a fuel preserver if your going to do this.
If it was an aluminium tank I would have suggested checking for pin hole corrosion on the underside. Water could then enter due to the tank sitting in bilgewater.

[Mantaray]

now why would anybody want to use a CAV filter on an outboard?

anyway there's more to this than simply condensation but when half a lite of water in a 120 litre tank starts giving problems then there's more questions than answers

[Sahara53]

Wow guys I did not expect to get such a number of replies and I thank you all very much for your input. Pete certainly I'm using the Racor filter and yep the motor is the Yam115 2 stroke oil injected. Perhaps I need to move to Qld to find a result (and better fishing water!).
We keep the boat in Ardrossan (Yorke Peninsula) as I don't have a shed here at home and so it lives in a large farm shed. Certainly we intend to get it back here in the near future and take it to Goolwa and run it on the sheltered river water. Hopefully we will enjoy a lovely family day and the kids can enjoy being towed behind the boat (after all I can't let them get in and dirty the boat!!).
My thought is that perhaps a replacement stainless steel tank might be worth the effort and expense and I'll be using a fuel conditioner from here on in. I'll keep all posted later in the year.

Peter A.

[suttos]

Hi Sahara 53,

Well they have given you all the excuses there are, and they are probably all right.

However I would like to put this too you, condensation occurs when the atmosphere is colder than the fuel this will amount to ltrs of water if allowed to sit in a cool environment. We in the southern states suffer with condensation during the winter mainly and the way to fix it is either use the boat regularily , or, keep the tank full of fuel, or drain off the water.
If you are concerned about stale fuel, use premium as it maintains its octane rating for a much longer period. Normal 91 octane unleaded is shxt, goes off like nanas nighty and is only good for fords and holdens.

In europe you cannot even buy 91 octane rated fuel our premium is their standard unleaded.

suttos

[uripper]

Sahara53
Have become the expert on watery fuel (for my rig at least) by neccessity. Your probs could be caused by many factors as mentioned in previous posts so suggest following:
1. use fuel stabiliser additive if storing longer than 3months
2. check both the motor fuel filter & inboard line fuel filter before you crank engine
3. start engine & run in a tub or leg bag for 5mins (earmuffs no good - got to get backpressure on exhaust & up to operational temp)
3. check both the motor fuel filter & inboard line fuel filter again (take off & tip out)
keep spares of both filters handy & change if think damaged - do this before each trip & reckon you'll soon work out what is your water source - good luck - Mal M

[impulse492f]

I'll through in 2 cents worth (from personal experience)

My issue was brought to my attention on New Years Eve on Botany Bay (broke down and needed to be towed back).

The guy i bought it off never ever had water in fuel problem, I bought it and within 3-4 trips out had all sorts of issues. My Haines 492F (under floor 90L) has the filler cap positioned in the tub just behind the motor (forgive me if that’s not the correct technical term). Now this cap was a metal to metal screw thread which at first i didn't even think was a problem (stupid me). As I anchored in the Bay for some good fishing, the waves were washing in over the filler cap (all day) and due to the lack of gasket/o-ring the water entered the tank in litres.

Placed a rubber o-ring on the cap and haven’t had a problem since.

The other issue i had was some loose hose clamps which both leaked fuel and sucked in water as one of the lines draped down into the bilge (depending on the pressure in the tank). I would check your breather to see if it’s clear as this will affect the pressure in your tank and tighten up all your clamps.

Just a note on the condensation issue, people are saying that plastic containers are the worst and the less fuel the more condensation you get. So why is it that a 20L plastic fuel container that I’ve had sitting in the elements (sun in the morning, shade in the afternoon) with about 8L of fuel has had next to no water in it after 3 weeks??. I'm not arguing the point I'm just noting my observations.

[impulse492f]

now why would anybody want to use a CAV filter on an outboard?

Why wouldn't you Mantaray, can you please explain?

Quote from the Bias catalogue

"C.A.V. Diesel Filter Cat. 665 BIAS Price $88.90
Agglomerator filter. Uses a replaceable paper element. Water is collected in the base & drained through a bottom screw plug. Alloy base & head. Height 197mm, maximum diameter 107mm. Maximum flow rate 45 litres per hour. Has 2 inlet & 2 outlet ports with 1/4" NPT female threads. Comes with 2 blanking plugs, hose tails are optional extras. For petrol or petrol/oil mixtures use optional extra Cat. 666P Element Kit."

[billfisher]

Impulse492f.

The problem is only with the underfloor tanks which are vented to the atmosphere. The problem doesnt arise with sealed containers.