Water getting in gas tank

[trobinson017]

Hey all,

I have a recurring problem with water getting into my gas tank, usually after heavy rains. My boat is a '99 Seaswirl Striper 21ft. CC and sits on a lift, tilted so the bow is higher than the stern. Somehow, water gets under the deck and on top of the gas tank. I've been told by mechanics that the poly tank I have expands and contracts with hot days/warm nights and causes a separation between the interfaces on the tank and the tank itself. Water is getting in through those separations they say. I believe water is getting under the deck via two hatches I have in the bow that drain into the under-deck area to the bilge for pump-out. The gas tank is level with the channels under the console so the water flows right over the top of it, settling on top where it concaves a bit. I've opened it at times and found standing water which I sponge out. I've sealed the tank interfaces with silicone but water still gets in. I've tried to seal the hatches with plastic sheeting but still getting water. I can't afford a full cover for the boat. I have a W/F separator which helps when it's a little water but useless when it's a lot.

Has anyone else experienced this kind of problem? If so, how did you resolve it? I'm getting tired of wasting money on fouled gas I have to pump out of the tank.

TIA!

 

[Home Cookin']

Re: Water getting in gas tank

not sure what you mean by "interfaces." Is it the insertion points for fill/vent, guage, fuel line to motor? If so, those are areas which often leak. You probably need a better fix than silicon; I'd wonder if gas fumes are eating it away from the inside.

If "interfaces" are the surface of the tank, you need anew tank and you ahve a safety issue here.

You may have a leak at the fill cap/vent area too.

 

[trobinson017]

Re: Water getting in gas tank

Sorry for the lack of clarity. By "interfaces" I mean the ports on top where the electrical connection for the float sensor is and the fuel out hose. I've attached a pic to illustrate them.
I've labeled the ports in the pic. The entire area shown in the pic is slightly depressed (concave) and contains water after a heavy rain.


Thanks!

 

[dingdongs]

Re: Water getting in gas tank

i agree that it does look as if water has been laying around that area.
1/could cover each area in silicon maybe changing rubber seals too or;

2/make a spacer say 3/8"(old plastic chopping board etc) and use 2 rubber seals instead of the one already used,longer bolts too & fuel levels will change but means you will have a little in reserve.

3/a large ring of silicon around areas may stem flow to both areas.

 

[Silvertip]

Re: Water getting in gas tank

Silcone is not gasoline tolerant. It will swell and become more of a problem and it cures. If the tanks has proper seals it should not allow moisture inside.

 

[Home Cookin']

Re: Water getting in gas tank

As I suspected, those rustedout parts are the culprit. replace them

 

[trobinson017]

Re: Water getting in gas tank

As I suspected, those rustedout parts are the culprit. replace them

If I replace the sending unit part, does that entail replacing the float too? For that matter, does replacing either of them involve more than just unscrewing/unbolting, remove, put on new, screw/bolt on?

Thanks for all the info!

 

[The_Kid]

Re: Water getting in gas tank

Like Silvertip said, silicone is not the right stuff to use. Get some Permatex Form-A-Gasket? No. 2 Sealant. Here's a clip from the data sheet.

"Chemical / Solvent Resistance
The product retains effective properties in contact with water, ethylene glycol, gasoline, motor oil, transmission fluid and sea water"

Pull the sending unit and fuel outlet loose. Clean all of the surfaces then put a bead of the Permatex on the tank, put the gasket down and put another bead of the sealant on top of the gasket. Put the 2 units back in and tighten them down.

Data sheet if you want more info.
http://www.permatex.com/documents/tds/automotive/80016.pdf

 

[wellsc1]

Re: Water getting in gas tank

The Kid,

Your reference to Permatex Form-A-Gasket No. 2 Sealant is exactly what I was looking for. Based on other information provide in this and other threads, I can expect to find a rubber gasket under the sending unit plate. If it's in good shape, I'll re-used it with a fresh coating of "sealant" on both sides. I'll remove any old sealant with isopropryl alcohol.

Again iboats forums rocks!

tnx...wellsc1

 

[trobinson017]

Re: Water getting in gas tank

As I suspected, those rustedout parts are the culprit. replace them

If I replace the two parts, are they just generic or do I need to get ones specific for my gas tank, fuel gauge, etc? I'd think the fuel outlet just has to be the right diameter for the existing hose. But the sending unit is something I know very little about.

 

[fjkiepe]

Re: Water getting in gas tank

Hey all,

I have a recurring problem with water getting into my gas tank, usually after heavy rains. My boat is a '99 Seaswirl Striper 21ft. CC and sits on a lift, tilted so the bow is higher than the stern. Somehow, water gets under the deck and on top of the gas tank. I've been told by mechanics that the poly tank I have expands and contracts with hot days/warm nights and causes a separation between the interfaces on the tank and the tank itself. Water is getting in through those separations they say. I believe water is getting under the deck via two hatches I have in the bow that drain into the under-deck area to the bilge for pump-out. The gas tank is level with the channels under the console so the water flows right over the top of it, settling on top where it concaves a bit. I've opened it at times and found standing water which I sponge out. I've sealed the tank interfaces with silicone but water still gets in. I've tried to seal the hatches with plastic sheeting but still getting water. I can't afford a full cover for the boat. I have a W/F separator which helps when it's a little water but useless when it's a lot.

Has anyone else experienced this kind of problem? If so, how did you resolve it? I'm getting tired of wasting money on fouled gas I have to pump out of the tank.

TIA!

Hi I have the same problem as you have. Is your problem resolved? How did you repair

 

[fjkiepe]

Re: Water getting in gas tank

Hi I have the same problem you had. Is your boat fixed? how did you repair? did you follow the suggestions submitted and re gasket the fittings on the tank

Thanks fred k

 

[trobinson017]

Re: Water getting in gas tank

Hi I have the same problem you had. Is your boat fixed? how did you repair? did you follow the suggestions submitted and re gasket the fittings on the tank

Thanks fred k

Nope. Problem not fixed. I've been running off a 6 gallon portable external tank. I may address the problem
this season.

Trob

 

[Home Cookin']

Re: Water getting in gas tank

Nope. Problem not fixed. I've been running off a 6 gallon portable external tank. I may address the problem
this season.

Trob

Wow. For three years. Can't get very far with a 130 on 6 gallons. I assume (hope!) your in-hull tank is empty!

Your problem, if you have propertly sealed all the insertions in the top, is probably your fill cap. replace it.

if you have the kind that vents seperately, the vent hole is more likely the problem.

I assume you are keeping your gas fresh and treated, too. A big tank, seldom used, will get watery from the E10 and the atmosphere.

 

[trobinson017]

Re: Water getting in gas tank

Wow. For three years. Can't get very far with a 130 on 6 gallons. I assume (hope!) your in-hull tank is empty!

Your problem, if you have propertly sealed all the insertions in the top, is probably your fill cap. replace it.

if you have the kind that vents seperately, the vent hole is more likely the problem.

I assume you are keeping your gas fresh and treated, too. A big tank, seldom used, will get watery from the E10 and the atmosphere.

Dang, has it been three years??? Time flies!! We use our boat mostly for cruising in our local waters off the Gulf of Mexico.
Believe it or not, the 6gal gets us pretty much anywhere we want to go.

For the in-hull tank, I pumped out the bad fuel. It's been sitting empty. I need to get a new sending unit
and fuel-out port. When I do, I'll be able to look into the tank to try and determine if any gunk is still in there
before putting on the new components. I don't use ethanol gas anymore after I found a station not far from home
that sells non-ethanol. Another thing that's helped keep water out is taking out the hull drain plug when on the lift.

Thanks for your comments!

TRob

 

[Grub54891]

Re: Water getting in gas tank

Many times its just the o-ring on the fill cap thats letting water in,usually the first place I look.

 

[frantically relaxing]

Re: Water getting in gas tank

If water can get in, gas and fumes can get out. Glad you're using a separate tank--

 

[h2odick]

Re: Water getting in gas tank

deleted.

 

[Chris1956]

Re: Water getting in gas tank

Trob, A lot of Seaswirl boats have the same issue. The plastic tank from Skyline is the issue, as they put steel fuel pickup fittings on the tank. Now that may work for freshwater, but not in St. Pete. I had the same issue. I used a bronze garboard drain fitting, and a brass flush bushing to replace the fuel pickup fitting. The garboard drain needs to be drilled to match the original bolts in the tank, and a gasket needs to be used to seal it. Permetex #2 is always soluable in gasoline, so don't use that.

The fuel gauge pickup is usually stainless steel. Maybe you can replace yours with SS?