Water in Fuel Tank

[Grady131313]

Hi All,

I am new to this forum and appreciate everyone's help. We have some issues with water in our tank. We removed the gas and polished the tanks and put new gas in and the boat ran great for the few hours the marina ran it. The boat then sat for a few weeks (a ton of rain). When we went to run it again, we noticed the engine knocking and then shut off (approx 30 minutes of running). We checked our separators and there was a decent amount of water in it. Our marina then checked and likely poked the top of the tank and found a very small pin hole. The hole was smaller than the tip of a pen. They are now telling us we should replace the tanks. The local marine store told me I could fix the small pinhole with Marine Tec (I have read the posts about this). I inspected the tanks as well as I could (both visually and with my hands where I couldn't see) and did not find any other corrosion or issues with the fuel tank. There is zero smell of gas and there is about 50 gallons in each tank (150 g tank).

I checked the fuel filler caps and the o-rings were dry and cracked (one broke when I took it off). These O-rings have not been replaced in at least 7 years. I also checked my vent (port side) and the inside tube was straight down. I put that into an upside down U. I plan on using an endoscope inspection camera to look at the tank again to ensure no additional corrosion.

Assuming no additional corrosion, my current plan is to take the 50 gallons out of the tank and put new fuel into the boat. 2. Treat the tank with k100, 3.continue to monitor the tank for additional corrosion, 4. Replace tank in next 1-3 years

My questions are:
1. Would you have marina siphon the water or would you replace all fuel?
2. Could my water problem really be from the fuel refill gaskets?
3. Adding k1000 do anything

Thank you!

 

[Doc Stressor]

If you were using E10 fuel, dump the gas. Once phase separation has occurred, most of the ethanol will be in the water phase. The octane rating of the remaining fuel will be below that required for proper combustion and knocking will occur that will eventually damage your pistons. If you are using Rec90 non-ethanol fuel, you will be fine just removing the water.

You will likely be able to get by for a season after sealing the hole and replacing the gaskets. But if you have one small hole you may wall have more. Since you can't access the sides and bottom of the tanks, you won't know what is going on there. If you are using straight gas you could just keep checking for water. But you are just postponing the inevitable.

I don't know what K1000 is or does.

 

[Grady131313]

Thank you very much

 

[Ky Grady]

Probably K100,,, fuel treatment, engine cleaner, water removal, snake oil.

 

[seasick]

Absolutely possible that the o-rings allowed water to seep in. I would siphon/pump out the water on the bottom of the tank. Probably no need to toss all the gas. Patch the hole for now bit I am not sure if I would use marineTex. Maybe it's OK, it's just not what I would think of first. I would clean up the spot and apply JBWeld.
As to whether the pin hole could allow all that water to seep in; If it's on the top of the tank and that area is typically dry, then no, it probably wasn't the source. If there is water AND it pools on top of the tank, then maybe. Do the simple things first.

 

[seasick]

Forgot to add: Carry a spare water separator and engine gas filter as well as the tools to change them if needed.

 

[Hookup1]

I have a lot of experience with this issue. It is difficult to troubleshoot. Most likely source of water in tanks is your fuel fill o-rings. It's difficult to get enough water in thru pin holes on the tanks. Epoxy over them. They are more likely to leak fuel not let water in. You likely have phase separation if a lot of water got it. The math has never worked for me to explain how much water I was getting out - water was getting in somewhere else.

Additives like K100 or dry gas products can not handle large volumes of water (couple of quarts). Picture below is water that I worked out of my tanks using the Sierra filters. Run it for a while then dump both fuel filter cans to see what you got.

Getting ALL the water out of the tank is difficult. Polishing doesn't really stir it up enough to get the bottom layer. I would recommend Sierra clear bowl filters. Run the boat and shake it up! Remember your boat processes less than a gallon a mile. It taks a while to suck it up. Look at this post...

2007 222 FISHERMAN WATER GETTING INTO TANK

I have had this boat 2 years . The end of last year i had to pull boat , motor would not run. The mechanic found water some 20-30 gal in gas tank . He re did vst assy filters all, vent for tank . new o ring on fill cap. Pulled all water out of...

www.greatgrady.com

Getting rid of all the gas is difficult and expensive. I have never found anyone who would do it. I wound up using it. Add some premium fuel and run it out.

Let me know if I can help...

Cheers!

 

[PointedRose]

Patch the hole for now bit I am not sure if I would use marineTex. Maybe it's OK, it's just not what I would think of first. I would clean up the spot and apply JBWeld.

Completely agree - JB weld not marinetex if that’s the route you go for now. That said, if they found one pin hole, there is probably another somewhere else.

 

[Ky Grady]

Hate to say it,,,, but one pinhole means more to follow. My tanks were '04 and they developed leaks. What started as a small hole in the bottom developed into this with a little poking around.

 

[seasick]

One additional thought.
If you use E10 gas and will for the refill, don't add any of the treatment you mentioned. Just add some fresh gas, say 20 gallons and see how things go. Continue to add gas in smallish batches till you are confident that all is OK.
The reason for adding small batches is that if it gets contaminated or there is a water issue, you will have 20 gallons of bad gas to dispose of instead of a lot more.
The ethanol in E10 acts like that additive, it will absorb some water and that burns of in the engine.
You vent is on the outside of the hull? There should be an upward loop but more importantly no downward loop.

All that said, 20 gallons of water is a lot. Had you refilled the tank just prior to the layup period or before the first outing after the layup? It is possible that you got a load of bad gas.

 

[seasick]

Hate to say it,,,, but one pinhole means more to follow. My tanks were '04 and they developed leaks. What started as a small hole in the bottom developed into this with a little poking around.

View attachment 22989
View attachment 22990

Where were those holes? Top or bottom surfaces?

 

[Ky Grady]

Where were those holes? Top or bottom surfaces?

These were bottom of main. If OP has pinholes on top, really needs to pull tank and check bottom. The top of mine was ok, a few corrosion spots here or there, the big culprit was on the bottom. I could look into my tank from sending unit hole and see a dark area, couldn't see the holes until I pulled it.

 

[Grady131313]

I have a lot of experience with this issue. It is difficult to troubleshoot. Most likely source of water in tanks is your fuel fill o-rings. It's difficult to get enough water in thru pin holes on the tanks. Epoxy over them. They are more likely to leak fuel not let water in. You likely have phase separation if a lot of water got it. The math has never worked for me to explain how much water I was getting out - water was getting in somewhere else.

Additives like K100 or dry gas products can not handle large volumes of water (couple of quarts). Picture below is water that I worked out of my tanks using the Sierra filters. Run it for a while then dump both fuel filter cans to see what you got.

Getting ALL the water out of the tank is difficult. Polishing doesn't really stir it up enough to get the bottom layer. I would recommend Sierra clear bowl filters. Run the boat and shake it up! Remember your boat processes less than a gallon a mile. It taks a while to suck it up. Look at this post...

2007 222 FISHERMAN WATER GETTING INTO TANK

I have had this boat 2 years . The end of last year i had to pull boat , motor would not run. The mechanic found water some 20-30 gal in gas tank . He re did vst assy filters all, vent for tank . new o ring on fill cap. Pulled all water out of...

www.greatgrady.com

Getting rid of all the gas is difficult and expensive. I have never found anyone who would do it. I wound up using it. Add some premium fuel and run it out.

Let me know if I can help...

Cheers!
View attachment 22987

Thanks all. Here is the gas we pulled out from one tank, the other tank seemed fine. Crazy that the marina didn’t mention a 2 part could be the problem, ha! The gas came out cloudy and then when it sat for a minute looked like this. A couple of service places said it looked like it wasn’t phase separation, but was gas and water. We polished the tanks and removed gas 2 moths ago so this gas is only 2 months old. Thanks again. I wish I found this site earlier.

 

[Grady131313]

As I said, I am new here. I only replied to Hookup1. Thank you all for your help. Here is the gas we pulled after it sat for a minute or two.

 

[Doc Stressor]

You can get lucky and only have partial phase separation with E10 as long as the fuel and water are not agitated. Such as with a boat sitting at a mooring. But you can't get around the chemistry and you have no way of knowing the octane rating of the fuel phase.

Phase Separation

Crap! I can't link to the PDF I wanted. Here is an image of the relevant part:

 

[Hookup1]

Is your problem solved or has it come back? If it's back pull can filter and dump in a jar. Give it a minute to separate out. Fill the can back up with fresh gas. Repeat the same on the filter under the engine cowling. Run the boat for a few hours on the water and repeat filter dump.

A gallon of E10 suspends FOUR (4) TEASPOONS of water per gallon of fuel before phase separation. That's 0.41%. About 1/2 gallon water for 100 gallons of E10. That is not much.

You really can't tell by looking at it. Your fuel has no ethanol in it.

 

[Grady131313]

The marina reported that the fuel is a mix of 10% mid-grade fuel with Valtech, which is marine grade, low ethanol fuel designed specifically for marine engines. The marina said they could pull the water out from tank (it is on a dock). Should I have them take the water out or should I remove all of the fuel (about 50 gallons). If costs were the same, what should I do? I dont want to be left with lower octane gas and get the engines choking - seems like I then could have other issues to fix. Thanks!

 

[leeccoll]

If its me, I would take it all out=cheap insurance.

 

[Grady131313]

Is your problem solved or has it come back? If it's back pull can filter and dump in a jar. Give it a minute to separate out. Fill the can back up with fresh gas. Repeat the same on the filter under the engine cowling. Run the boat for a few hours on the water and repeat filter dump.

A gallon of E10 suspends FOUR (4) TEASPOONS of water per gallon of fuel before phase separation. That's 0.41%. About 1/2 gallon water for 100 gallons of E10. That is not much.

You really can't tell by looking at it. Your fuel has no ethanol in it.

It never went away and we have not used the boat. We ran the boat for about 10 minutes and one engine sounded good (different tank) and the other definitively started to choke out a bit. We shut the engines down, emptied the separator and the water filters on engines and started them up again and engine started to choke again. We shut the engines off and emptied the separators and filters again and added gas to both. We wrote to GG for advice. Marina is hopefully pulling the gas out today or tomorrow and adding 30 gallons to each tank. We will then go down and run the engines with new gas, check filters and empty them and check for water and hope it is resolved. We do have bowls on filters and will monitor.

 

[Hookup1]

For your peace of mind get all the old gas and water out of the tank. Then run the boat and start checking the fuel filters. Maybe switch to Sierra clear bowls so you can monitor any water in the fuel.

Also ask the marina how they are going to get the last drop of water out. If it's from the pickup its not going to happen. If they pull the sending unit and shift the boat around and force fuel to a corner then maybe.

Not to be a dark cloud but you need to figure out how the water is getting into the tank otherwise it will be back.

A few years ago I tried to get rid of old fuel but I could not find anyone who would take my old fuel. Everyone told me to burn it up. Which I did. I got the water out as above and then added premium fuel.