Water moisture in the tank?

Cabezon1

Well-Known Member
I run a couple of yami 225 on my boat. Recently, I have had some problems with the engines, usually one at a time, bog down and stall on me while trolling or off plane. I would squeeze the primer balls and the engine would start again no problem. This usually happens a couple of times in a 1 hour period. I suspect there might be water moisture in my fuel tank. I have already changed the fuel filters but the problem persists. I have been told adding methyl hydrate as a water remover should help. Any suggestions? I really don't want to drain the tank if I don't have to ? Any good fuel additive that fellow forum members use to remove water from fuel?
 
Methyl hydrate is the best. I keep a bottle on the boat.
 
Check your Racor type water separators/fuel filters and drain any water if necessary and then monitor them. If you don't have them, -- install a couple. You should be able to see water building up in the clear portion of the water separator which needs to be drained periodically through the drain on the bottom of it.

Keep your tank full as much as possible, especially for storage and if it is Aluminum. This prevents warm air condensation on the cold tank wall from adding water to the fuel and in the case of Aluminum helps prevent tank corrosion.

Fuel cap assemblies get old and the threads get worn and some times let in water spray or rain water.

There are other things to check with this problem:

Make sure that you do not have any small sucking air leaks with any of the various fuel line connections. New fuel lines and clamps periodically is a good things and also make sure that any of the screw in brass fittings in the fuel line system have the fuel type (yellow) plumbers tape wraped on the threads and check/replace your squeeze bulbs if you have any doubts. If you have bronze fuel line cutoff valves make sure the threads have the tape and if they are really old and nothing else works consider replacing them.

Make sure your tank vent and hose is clean and fully functional. Spider web material is a problem with blocking them or partially blocking them for example. This can cause early tank failure and possibly problems like you are describing.
 
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To me it sounds like you have more than a "water moisture" issue. If you have a persistent problem I would suggest you look at the big picture and see if there is any other way water might be getting into your tank. The reason I suggest this is because I had a similar issue with my boat. My overflow/breather pipe on my boat is on the side of my boat roughly amidships and what I finally figured out was that in rough seas when the boat was pounding and spray was travelling down the side of the boat a small amount of water would get into the overflow and go right into the gas tank.
Not sure if this could be happening to you, but again, if your problem is persistent I would be looking everywhere.
Moisture/condensation shouldn't be an ongoing thing.

After re-reading your post, when you change your fuel filters are they full of water? Maybe it's not water in your filters causing your motors to stall?
 
Was hoping it was moisture and there is an easy fix. When I changed the fuel filters last month there was about 1/4 of water in the one of the filters and 1/8 in the other. The reason I suspect it might be fuel is because both engines, more so the stbd engine have stalled at one time or another and squeezing the primer balls seems to fix the problem, albeit temporary.
 
The fact that both of your motors are having the same problem does suggest that it may be the fuel/tank plumbing systems that is problematic. I assume both of your motors are on their own separate complete fuel line system right from the main tank back. Less likely that both fuel pumps or some other motor problem would occur on both motors at the same time causing the same symptoms.
 
Drain em...... Those injectors are gonna go belly up. Water+ injectors = injector failure
 
Sounds more like your sucking air, especially if it's when your only using one engine.
Check clamps and connections like rockfish is saying.

If you don't find anything obvious, try disconnecting the motor not being used or put a fuel shutoff in to isolate the motors from each other.
I had the same problem but with my kicker and main.

Methyl hydrate is hard on seals and hoses, use sparingly.
For water,
I started using TerraClean after getting a bad batch of fuel at work. The stuff is amazing at dealing with water, it says it's for diesel but it works on gasoline as well.
It literally makes water combustible.
http://www.terraclean.net/product.php?id=27
It's available at ford dealers, the power strokes are extremely sensitive to water and contamination.
 
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To me it sounds like you have more than a "water moisture" issue. If you have a persistent problem I would suggest you look at the big picture and see if there is any other way water might be getting into your tank. The reason I suggest this is because I had a similar issue with my boat. My overflow/breather pipe on my boat is on the side of my boat roughly amidships and what I finally figured out was that in rough seas when the boat was pounding and spray was travelling down the side of the boat a small amount of water would get into the overflow and go right into the gas tank.
Not sure if this could be happening to you, but again, if your problem is persistent I would be looking everywhere.
Moisture/condensation shouldn't be an ongoing thing.

After re-reading your post, when you change your fuel filters are they full of water? Maybe it's not water in your filters causing your motors to stall?
I think daddystoy could be onto something. Where are your vents placed - from your tanks? Are they the throughhull freeboard types - where splashing can get into them? I had that problem on a river jet boat before - bad design - but easy to fix..
Fuel-System-1.jpg
0509-perko.jpg
 
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If I were betting I would be going with sucking air leaks, possibly a number of them, and possibly bad internal bulb valves, especially if the bulbs are not firming up or going soft after a while. Be very careful messing with the through hull vents as that is a major safety feature and keeps gas filling overfill spray out of the boat and also keeps out heavier than air gas vapour which will settle down in the bilge. The federal government requires that built in fuel tanks be vented outside through the hull. I would like to think that a factory boat large enough to run 2 x 225 motors is well enough designed to keep water out of the vent and possibly has some sort of ball valve if necessary - unless of course some previous owner messed with it. It may be possible that in very heavy seas that a small amount of water gets forced into the vent hose but again I would like to think that this is very uncommon. We check and drain our water separators periodically and never have much in them but some is normal. Now if you are having to drain them a lot perhaps something is up. Never had a problem with the vent on our boat. Don't look for the Zebra's first as what you are going to find is the problem is most likely a more common animal.

When you drain your fuel water separators, put a tiny drop on your finger and taste it and see if it is salty or fresh.
 
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Boat is a 2000 Grady 268 so I am pretty confident the through hull vents are good. I will try to fix it first with fuel additive when I run close to empty. If that doesn't work I will probably change the fuel water separators again, the primer bulbs and maybe the fuel lines from the tank to the engines. If all fail, then it's time to drain the tank. Boating, or the fixing of problems associated with boats, it's a labor of love. I will keep you guys posted.
 
Boat is a 2000 Grady 268 so I am pretty confident the through hull vents are good. I will try to fix it first with fuel additive when I run close to empty. If that doesn't work I will probably change the fuel water separators again, the primer bulbs and maybe the fuel lines from the tank to the engines. If all fail, then it's time to drain the tank. Boating, or the fixing of problems associated with boats, it's a labor of love. I will keep you guys posted.
I wasn't thinking that the installation was leaking - put rather the placement and direction of the vents could allow splashing up into the vent tubes. That's the "poor design" that sometimes happens on boats. You should be to loosen and turn the vents pointing towards the stern - the "easy fix" - to keep splashing from the bow from entering the vents.
When you drain your fuel water separators, put a tiny drop on your finger and taste it and see if it is salty or fresh.
good point, RF!...
 
In order for rain and spray to get past the vent down the vent hose and into the tank would it not require not only a poor positioning of the vent opening but also poor positioning of the vent hose? As I understand it the vent hose can first goes up a little before it drops down to the tank so that under normal circumstances water that got past the vent would simply run down and back out the vent even with very low air pressure being sucked in the larger diameter vent hose as fuel is sucked out of the tank.
 
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You are right rockfish - properly installed - it should. Doesn't mean it was however. Even credable boat builders occasionally have someone helping the install who doesnt...
 
i know you are noting water problems...... i have seen and had it happen to me that a fuel supply line can become soft over the years and when a high vacuum like a pair of 225 want fuel , this could be causing a temporary collapse of a fuel supply line. mine was a total biatch to figure out... i thought it was water problems at first...

and dont forget to drain your high pressure filter.. it also has a separator built in and once water gets past this last safety, your injectors will pay the price.

dint read carefully, if its at troll , most likely an air leak!
 
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If you have a little bit of water in the filter bowls it just shows they are doing their job. There is a school of thought that you should run the tanks down regularly to allow the fuel to agitate the water and sediment to get it into suspension and into the filters to be removed regularly with filter changes vs keeping tanks as close to full as possible to try to keep moisture out of the fuel and filters. If you can pump it back up with the balls I would be looking at another filter in the system or most likely an air leak in the fuel plumbing (hoses, clamps, valves, pick ups, ect) or less likely.................junk in the tank blocking/ restricting fuel flow at the pickups. Hose collapse would typically be a WOT issue but the bubbles of a small air leak turning to an empty bulb vapor lock would make sense when trolling.
 
If pumping the primer bulb temporarily fixes it I doubt it's a water issue. If it was water priming it would push the same troublesome product into the system, it's a delivery issue.
 
I had the same problem and it turned out to be the Fuel filler cap. But in the mean time i pulled my gas tank and had the vent tested and the sending unit on top as that can be a problem also. Unless you can see it that could be letting water into the tank. I got all new plumbing and revented the tank from the side of the boat.. My mechanic kept telling me to get it fixed as the water is not good for motors.
 
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