water in Outboard fuel tank

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Spyro

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I went to start the Johnson 3.5 a few days ago. It wouldn't start. I'd had the problem before and there was water in the fuel tank. First thought was check for fuel so I removed the drain screw on the underside of the carb bowl And again water came out instead of fuel. I let it run until it was fuel then shut off the valve refitted the screw and after a few pulls the engine ran fine.
My thoughts the last time this happened were that possibly I had left the vent open on the tank and rain water had got in as the engine is stored on the pushpit. This time it was definetly closed and no water could have got in as it was airtight (it hissed when I opened it).
Where did it come from? Is there water in fuel that can separate as in condensation then get back into the fuel and remain as water sinking to the bottom of the tank then into the carb bowl? The engine was last used about 6 weeks previously and was fine.
 
Could rainwater be running down inside the cover, say down the starter cord, and getting in through the air intake? I can't think of any other ingress route, post-filling, apart from through the tank vent or through the air intake.

Water dispersed in the fuel (somehow) or condensation over 6 weeks could not generate so much separated water.

Richard
 
We have a 2.3 honda and about twice a year we have problem and have to strip the carb every time we find a small amount of water , again like you we have no idea where it comes from , I all way turn the fuel tap off and empty cab before remove the engine back on to the boat so the carb is near alway run dry , I wonder if that's the problem , the case now is the carb bowl now as rust , which is another problem , so I am going to have to replace it next year . Honda as a rule makes a good engine , I not sure what happen when they made the 2.3 , lost of mild steel bits that rusted away , never buy another 2.3 .
 
We had a similar problem with our 4HP Evinrude. The local boat yard recommended a product called 'Dry Fuel' Made by Wynns. You add a dose of the stuff to your fuel tank and it allows any condensation to mix with the fuel and be burnt without it causing a problem. Sounds ridiculous but since we started using it we've not had the problem again. It's not expensive and a bottle of it lasts for ages in a little outboard.
Hope this helps.
 
Fuel evaporates from the carb. This cools the carb.
Damp air will create condensation in the carb, some of this will end up in the float bowl.
 
Spyro said:
I went to start the Johnson 3.5 a few days ago. It wouldn't start. I'd had the problem before and there was water in the fuel tank. First thought was check for fuel so I removed the drain screw on the underside of the carb bowl And again water came out instead of fuel. I let it run until it was fuel then shut off the valve refitted the screw and after a few pulls the engine ran fine.
My thoughts the last time this happened were that possibly I had left the vent open on the tank and rain water had got in as the engine is stored on the pushpit. This time it was definetly closed and no water could have got in as it was airtight (it hissed when I opened it).
Where did it come from? Is there water in fuel that can separate as in condensation then get back into the fuel and remain as water sinking to the bottom of the tank then into the carb bowl? The engine was last used about 6 weeks previously and was fine.
Click to expand...

BioEthanol petrol....

If you get not a lot of water in your tank (as low as 40 ppm) then phase separation can (will!) occur

Read more here
http://epa.gov/oms/regs/fuels/rfg/waterphs.pdf

Don't ask how I know this. All I'll say is I have a petrol station. :(
 
Whilst the motor is running damp air is being drawn into the fuel tank, via the breather.
When left the overnight temps will result in the water in the air condensing inside the ful tank and running down to the bottom of the tank. This water will get drained into the carb as the pickup is at the bottom of the tank.
I found if there is water in the fuel it's best to empty the fuel tank completely (tip it upside down). This allows a sump volume at the bottom of the the tank, below the outlet for water to collect. Until you do this the water will always settle to the level of the outlet after use.

Bizarely, running the carb dry will exacerbate the problem as you run water-rich fuel into the float chamber every time you go to start the motor.

Works for me.
 
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lw395 said:
Fuel evaporates from the carb. This cools the carb.
Damp air will create condensation in the carb, some of this will end up in the float bowl.
Click to expand...

I usually empty the carb bowl via the drain plug if I'm not going to use it for a while. I'm now thinking this could be causing the problem.
 
Lakesailor said:
Whilst the motor is running damp air is being drawn into the fuel tank, via the breather.
When left the overnight temps will result in the water in the air condensing inside the ful tank and running down to the bottom of the tank. This water will get drained into the carb as the pickup is at the bottom of the tank.
I found if there is water in the fuel it's best to empty the fuel tank completely (tip it upside down). This allows a sump volume at the bottom of the the tank, below the outlet for water to collect. Until you do this the water will always settle to the level of the outlet after use.

Bizarely, running the carb dry will exacerbate the problem as you run water-rich fuel into the float chamber every time you go to start the motor.

Works for me.
Click to expand...

"running the carb dry" by shutting off the stopcock and running the engine till it stops doesn't actually run the carb dry it still leaves fuel in the carb bowl. That's why I have been draining the bowl after use. I had problems with a gummed up bowl previously so have been doing that but now I'm wondering if that is causing the water in the bowl. I guess the only answer is to use it more often.
 
Lakesailor said:
Whilst the motor is running damp air is being drawn into the fuel tank, via the breather.
When left the overnight temps will result in the water in the air condensing inside the ful tank and running down to the bottom of the tank. This water will get drained into the carb as the pickup is at the bottom of the tank.
I found if there is water in the fuel it's best to empty the fuel tank completely (tip it upside down). This allows a sump volume at the bottom of the the tank, below the outlet for water to collect. Until you do this the water will always settle to the level of the outlet after use.

Bizarely, running the carb dry will exacerbate the problem as you run water-rich fuel into the float chamber every time you go to start the motor.

Works for me.
Click to expand...
Normally, it only takes a tiny drop of water to affect the carb, while the tank will hold several cc's at least, but yes, tip it all out and check for water, dead spiders etc.
Also clean any filters, blow through the through the tap and hoses etc.

The most reliable outboards are always those that have been used a few times in the last week....
 
Spyro said:
"running the carb dry" by shutting off the stopcock and running the engine till it stops doesn't actually run the carb dry it still leaves fuel in the carb bowl.
Click to expand...
It drains enough out until the suction won't pull any fuel up the emulsion tube or drops below the bridge in the carb throat where the needle enters the main jet, depending on you carb type. This means when you turn on the tap some water will run into the fuel bowl and will go to the bottom, where the pick-up for the jets is situated.
 
Lakesailor said:
It drains enough out until the suction won't pull any fuel up the emulsion tube or drops below the bridge in the carb throat where the needle enters the main jet, depending on you carb type. This means when you turn on the tap some water will run into the fuel bowl and will go to the bottom, where the pick-up for the jets is situated.
Click to expand...
Surely if there is water that is going to enter the tap, it's going to the float bowl, regardless of whether the bowl starts empty or full?
At one time I had frequent water-carb experiences, using an outboard a lot in autumn, and storing it somewhere pretty damp.
I installed an inline filter which trapped absolutely zilch.
I just got adept at draining the carb into a plastic tray and pouring the fuel back in the tank, hopefully minus the water!
 
I don't think you have grasped what I explained. You said "it still leaves fuel in the carb bowl."
I merely said that it doesn't leave the bowl full and so water will flow into it before you fire up. Which you won't.
 
Lakesailor said:
I don't think you have grasped what I explained. You said "it still leaves fuel in the carb bowl."
I merely said that it doesn't leave the bowl full and so water will flow into it before you fire up. Which you won't.
Click to expand...

I didn't try to grasp anything all I said was that you can't actually run the carb dry. Yes the valves and jets won't have fuel in them to gum up but shutting off the tap and running the engine until it stops still leaves fuel in the carb bowl, to get that empty you have to undo the drain plug on the bottom of the bowl.
 
Hmm. A bit of a problem getting my message over here. Draining the fuel bowl is worse. Then you import allyour fuel into the crab when you open the fuel tap. If there is water in the tank you will get even more water in.
I have never subscribed to the "running 'till dry" ethos. I also haven't had water in the carb problems. The only time I did was under way when the water in the tank got through once the fuel in the carb had been used.
Water in the tank is the enemy. If you use a remote tank it's worth emptying it every now and then. You can empty it into a conatiner and capture the fuel, leaving the water.

The bit at the bottom is water (it looks yellow because of the surroundings and internal refraction. I decanted off the top part and re-used it, just to prove to myself it genuinely was fuel)

Anyway, that's my thoughts.

waterinfuel.jpg
 
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I understand what you are saying. I have tried to fix one problem. (Gummed up fuel in the carb bowl) by running dry and draining the bowl and seem to have caused another. Like I said earlier I think I'm just going to have to use it more often.
 
When I leave my outboard for more than a week or two I open both the carb drain plug (I have permanently attached a couple of inches of fuel pipe to the barb) and the tank tap and drain the entire contents of both carb and tank back into my poly fuel can.

I can check the poly can for water when it gets low but in the meantime, when I refill the tank, it's only the fuel I'm decanting back in.

Richard
 
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