Disappointing End to the Boating Season - Return of the bad fuel issue

[Scuba_ref]

So earlier in the season I had some issues with water in my fuel causing phase separation; to resolve it I ended up draining my tank completely and since then I have been adding Stabil with every fill up or top off. This worked great while we were camping and using the boat every day, all day long.

Well fast forward to two weeks ago where we took the boat out after it had been sitting for about a week and I had the same gas issue even though I have been adding stabil. I pumped out the gas at the bottom of my tank (not all the gas, just until it ran clear again) and got the engine running. Since that instance I started using just ethanol free gas.

So today (probably our last day over 90 degrees for the year) I take my kids and a few friends to the river and again I get sidelined by phase separation in my fuel. I know there was still some of the E10 fuel in the tank, but I have added probably 40 gallons of E0. While at the dock I pumped out fuel until it was clear and then got the engines running, they would run for a little bit and then die, I would pump out more bad fuel and the cycle would repeat. Eventually the kids left as they had other plans for the evening, but I stayed at the dock and continued to work through the fuel until the engines idled fine for about 20 minutes. At that point I thought it would be safe to make a run up the river but as soon as I got up on plane the engines died again as more junk pooled at the fuel pumps so I gave up and came home.

Question I have: Do you think there is any way that water is getting into the fuel from some source other than with the fuel? At one point I wondered if maybe there was a small hole in my gas tank somewhere allowing fuel to get in, but whenever I open the fuel cap there is lots of negative pressure sucking air into the tank so I think it is sealed. Then I wondered if maybe there shouldn't be that much negative pressure and that the air being sucked in might be adding the moisture, but our air is pretty dry so I don't think it is that.

Basically I'm stumped. We didn't have any issues like this last year and none of the variables have changes between last year and this year.

Hoping someone might have a suggestion.

Thanks.

 

[Scuba_ref]

@Glassman what water/fuel separator did you install in your boat? I'm thinking it may be time to add a couple of those.

 

[Scuba_ref]

One other thought; I don't know how the fuel system vent works and wondered if water is getting in there, but again there is negative pressure in the tank when I open it to put fuel in so I'm guessing that the vent is working the way it should be!

 

[OrangeTJ]

Are you totally sure that the vacuum in your tank isn't causing your engines to starve for fuel and die? I had an atv that didn't vent properly, causing that issue. Opening the fuel cap would relieve the vacuum and let the engine run for 29 minutes or so until it starved again.

 

[Scuba_ref]

I am positive. I use the fuel pumps to pump out the affected fuel at the bottom of the tank and it comes out looking like milk. Thanks for the thought though.

 

[Gym]

@Scuba_ref. There should be NO negative pressure in your fuel tank. The purpose of the tank vent is to prevent that. A vacuum will cause the engines to shut down. As far as where the water is coming from, I'm not sure. Is your gas cap gasket in good shape? Was the gas cap ever replaced? Is it an OEM cap? Do you see or smell fuel in the bilge? Try blowing out the vent line. I would address the vacuum issue first.

 

[bronze_10]

I had a tractor trailer do that to me when the vent on the driver side tank failed. The truck shut off at highway speed.... I knew I had fuel and the gauge also read 3/4 full of fuel... once I rolled to a stop on the side of the road I got out and popped the tank lid.... when I did it sounded like a small bomb when off.... the tank was almost empty but the vent didn't let the passenger side tank drain fuel over through the cross over line...... as soon as I opened the lid all the air rushed in and the fuel began to transfer..... I know your concern is more about the bad fuel but if the vent isn't working right the tank could be drawing water or moister in from other areas... I agree with @Gym... address the vent then see where it leads you.

 

[Julian]

Yeah....there shouldn't be negative pressure.....

 

[4x15mph]

Have you caulked up around the screws that attached the fuel sender to the tank? Also, caulk up where the fuel vents connect to the tank. I think you are getting water to leak into the tank. I don't think you could be getting as much bad gas as you showed in your original post.

I have fuel/water separator filters that are made by Sierra. I think you can buy these kits from the Jet boat pilot store or Island Racing. I like the easy filter change each year since the old one's twist off and the new one twists on like an oil filter. The filter cleans the fuel and extracts any water.

 

[Scuba_ref]

@Scuba_ref. There should be NO negative pressure in your fuel tank. The purpose of the tank vent is to prevent that. A vacuum will cause the engines to shut down. As far as where the water is coming from, I'm not sure. Is your gas cap gasket in good shape? Was the gas cap ever replaced? Is it an OEM cap? Do you see or smell fuel in the bilge? Try blowing out the vent line. I would address the vacuum issue first.

I looked on the parts diagram and there is a check valve in the vent line. Does anyone know how to test this valve?

 

[Scuba_ref]

Have you caulked up around the screws that attached the fuel sender to the tank? Also, caulk up where the fuel vents connect to the tank. I think you are getting water to leak into the tank. I don't think you could be getting as much bad gas as you showed in your original post.

I have fuel/water separator filters that are made by Sierra. I think you can buy these kits from the Jet boat pilot store or Island Racing. I like the easy filter change each year since the old one's twist off and the new one twists on like an oil filter. The filter cleans the fuel and extracts any water.

Would you use regular silicone caulk? I'm wondering if I should put a small bead of caulk where the fuel pumps attach as well?

 

[Scottintexas]

I'm wondering how you're getting that much water in your tank, I don't think it would be because of a bad gasket on your fuel sender, how much water is that exposed to under the deck???? I know it's a possibility but it's has to be a very small amount. It is very confusing on how your getting that much water in the tank, it would almost have to come from either the fill line or vent line or bad gas to begin with.

I don't know how to verify if the check valve is working unless you just blow on the vent cap

Is your vent cap on the hull turned in a way it is facing up and maybe catching rain/water and the check valve ( #16) isn't working ?

 

[Scuba_ref]

We generally have a pretty wet cockpit environment as we are filling and draining fat sacs (manually attaching and disconnecting the tsumani pumps always results in a spout) and just having dripping wet kids climbing in the boat. On the last good trip out I had a group of boy scouts in the boat and so at the end of tubing and surfing I ran them through some high speed PWC type manouvers as well as a few half way sub moves (just enough to drench the boys sitting in the bow) all that meant there was a lot of water in the boat.

With regards to the check valve, I feel that it is probably not operating correctly - the fact that there is significant negative pressure (which I'm told there should not be). I think I might just order a new check valve as they are only $30. I bought some fuel resistant sealant that I will use on the sender unit screws and I think I will put some under the fuel pump flanges. I'm also thinking pretty hard about adding two racor fuel/water seperators, one for each engine.

The vent cap has two screened openings and (not being near my boat at the moment) I believe they are oriented down and aft. The aft opening is pointed slightly upward.

 

[itsdgm]

If you're building up a vacume in the tank wouldn't think that you would need to seal anything. That would be an indication of a pretty tightly sealed system. But like the others have stated, sounds like at the very least you have a vent issue. I suspected my fuel contamination issue possibly being caused by a newer storage cover that I'm using which is leaking worse than my old one. I suspect that some of the water is going right into the tank through the cover and down the vent. Sounds like yours might be plugged up. I'm wondering g if it's plugged up somehow from dust/dirt possibly being washed into ther?

 

[Scottintexas]

Dennis,
I looked at our schematics and it's the same as the 2005. If it was installed correctly or as indicated the loop in the system should stop non pressured water from getting into your tank, it would be good to take a look at the actual install.

Scuba Ref - since you mentioned you had boy scouts on the boat and I spent the last 10 yrs involved with them and you were emptying your ballast bags, any chance one of those boys used the hose as a water gun and it could have gotten inadvertently pointed towards the vent to force water down it ?? just thinking on how you could have gotten that much water in your tank,

 

[Scottintexas]

maybe somebody can chime in as to how much water it takes to make bad fuel,
if you pumped a gallon of milky fuel out was that an ounce of water, half a gallon of water ?

 

[Scuba_ref]

If you're building up a vacume in the tank wouldn't think that you would need to seal anything. That would be an indication of a pretty tightly sealed system. But like the others have stated, sounds like at the very least you have a vent issue. I suspected my fuel contamination issue possibly being caused by a newer storage cover that I'm using which is leaking worse than my old one. I suspect that some of the water is going right into the tank through the cover and down the vent. Sounds like yours might be plugged up. I'm wondering g if it's plugged up somehow from dust/dirt possibly being washed into ther?

Good points @itsdgm I did switch from a generic cover to the Yamaha delux cover in July, I would hope that isn't the problem. We did have a terrible fire season with unbelievable amounts of ash in the air coating everything. It is entirely possible that enough ash worked through the screens and then got washed down to the check valve. I think I will replace that valve. I currently have the boat in a bow up attitude encouraging all that heavy sludge to settle back at the pumps so I can pump out what is left in there.

With regards to the amount of water, if you get to 0.05% you will be at phase separation. Adding stabil gives you an additional 0.02%. That really isn't a lot of water.

With regards to the boys...let's just say that I actually had two tsunami pumps going so I'm sure you can imagine the scene.

 

[itsdgm]

Dennis,
I looked at our schematics and it's the same as the 2005. If it was installed correctly or as indicated the loop in the system should stop non pressured water from getting into your tank, it would be good to take a look at the actual install.

Scuba Ref - since you mentioned you had boy scouts on the boat and I spent the last 10 yrs involved with them and you were emptying your ballast bags, any chance one of those boys used the hose as a water gun and it could have gotten inadvertently pointed towards the vent to force water down it ?? just thinking on how you could have gotten that much water in your tank,

Thanks Scott for the info. I'll have to check that out.

 

[Murf'n'surf]

Questions and random thoughts that are in my mind.....

Are you sure that the tank was drained completely at beginning of the season?

Do you get fuel at the same place as you did before the initial water issue? If yes I think this might be your problem.

Do you smell or see fuel in the bilge after a fill up? If not, I think all penetrations are sealed tight.

Make sure the fuel vent screen/opening is facing aft or down.

Is there an o-ring on the fuel cap?

 

[4x15mph]

Would you use regular silicone caulk? I'm wondering if I should put a small bead of caulk where the fuel pumps attach as well?

Yes, you could use regular silicone caulk. I know my tank holds water on the top and sealing would be important. I read one post where someone had leaks around the screws that hold the fuel sender to the tank. It sounds like your boat may be different based on the other comments above.

The fuel vent would be another possibility and I am surprised if it does not face downwards.