replacing plastic gas tank with metal

[irish1985]

hi all. this was my first boating season. i have an '88 bayliner capri with an 82 mercury outboard (70 hp).

i currently have a 6 gallon plastic gas tank with a screw on/off vent cap on top of the gas cap. pictures below:




i've researched the forum and have read mixed things about leaving the vent open and closed while not in use.. primarily that moisture and rain can get in while it's open so it should stay closed... or the other point of view that it can essentially expand/blow up if it's closed so it should stay open. my tank is primarily in the sun everyday because it would be a pain to carry the gas can in/out every time i use it.. sometimes the tank expands so much that it looks like it's going to blow up, but i usually keep the vent closed while not in use due to fear of getting moisture in the tank.

nevertheless, i figure the best solution would be to replace the plastic gas can with a metal one that has an automatic vent. i have found this old mercury tank on craigslist, and have contacted the seller but haven't yet heard back.. i was wondering if anyone can tell if this is "self-venting"? anything else i should ask the seller, aside from rust? his ad says that it's mixed with the same 2 stroke that i'm currently using. here's a pic of it:



thanks in advance.

 

[UncleWillie]

Re: replacing plastic gas tank with metal

The plastic tanks is fine.

The Current Models do not have the capability to vent OUT except for a pressure relief button you press just before taking the cap off.
They automatically vent IN to prevent the tank from collapsing as the fuel is used.

They will normally "Swell up like a Baloon." OUT venting will happen if the pressure exceeds 5psi. (That's a LOT!)

You do NOT want a venting gas can, you want one that is sealed up tight.
If you leave the vented can in the boat you will soon have a boat filled with gas fumes.

If you leave the vent open all the time, you are not just venting "fumes" that is your hard earned Gas going to the wind.
You are actually the cause of the tank of "BAD Gas"

 

[MH Hawker]

Re: replacing plastic gas tank with metal

I have been using the plastic 6 gal tanks for 20 plus years, open the vent and forget it. Never had the first problem with water.

 

[emoney]

Re: replacing plastic gas tank with metal

Me neither. And, btw, metal tanks expand and contract too, they're just not as noticeable. As "they" say, fuhgetaboutit.

 

[EddiePetty]

Re: replacing plastic gas tank with metal

......and;

PLastic don't rust!

 

[jigngrub]

Re: replacing plastic gas tank with metal

Keep your boat covered!

You won't have to worry about water in the gas tank with an open vent and your boat will last longer. You're not doing your carpet, decking, or upholstery any favors by exposing them to the elements.

 

[irish1985]

Re: replacing plastic gas tank with metal

thanks for all of your responses.

i have a cover, but i believe it's intended for storage, so it's a total pain to work it around the ropes that are connected to my dock. i still put it on when i hear about storms in advance, but have admittedly gotten more slack about it as the season has gone on... mostly because it usually doesn't do a great job. i should get a new one, or at least put more time into trying to manipulate my current one. most of the prices i've seen on new covers are hard to justify for a 25 year old boat that's worth $1500... maybe a bimini top can remedy the issue a bit, as i hear it's mostly the sun that's destructive versus rain?

 

[UncleWillie]

Re: replacing plastic gas tank with metal

Keep your boat covered!

You won't have to worry about water in the gas tank with an open vent and your boat will last longer. You're not doing your carpet, decking, or upholstery any favors by exposing them to the elements.

And keep the tank vent CLOSED.
An open gas tank in a covered boat is a lead news story waiting to happen.

The boat gets hot under the cover.
The tank vents off fumes like crazy.
The cover makes sure the fumes have nowhere to go.
You can just see where this is going.

There is NO reason to leave the tank vent open.
The only complaint is that you do not like the cosmetic looks of the pressurised tank.
It was designed to withstand the pressure.
A warm 6 gallon vented fuel tank can loose 1 gallon every three weeks due to evaporation.

 

[irish1985]

Re: replacing plastic gas tank with metal

And keep the tank vent CLOSED.
An open gas tank in a covered boat is a lead news story waiting to happen.

The boat gets hot under the cover.
The tank vents off fumes like crazy.
The cover makes sure the fumes have nowhere to go.
You can just see where this is going.

There is NO reason to leave the tank vent open.
The only complaint is that you do not like the cosmetic looks of the pressurised tank.
It was designed to withstand the pressure.
A warm 6 gallon vented fuel tank can loose 1 gallon every three weeks due to evaporation.

i couldn't care less about the "cosmetic look" of a blown up tank, my primary concern was the tank exploding from pressure build up.. apparently that's pretty rare, which is good to know. another related question, lets say the tank is expanded, and i open it up to vent it out before taking it out on the water... is it dangerous to start it shortly after the tank has been vented because of fresh fumes lurking around the motor/battery? with this being an outboard there's no blower, etc but still seems a bit dangerous, no?

i'm a total noob with boats, so take it easy on me

 

[irish1985]

Re: replacing plastic gas tank with metal

while the edit-post function of the forum isn't currently working, i should clarify my first sentence in the last post..

i couldn't care less about the cosmetic look of a PRESSURIZED/EXPANDED tank... a "blown up" tank is a bit misleading in the context of what i'm talking about about here haha i most certainly DO care about a tank EXPLOSION!

 

[UncleWillie]

Re: replacing plastic gas tank with metal

while the edit-post function of the forum isn't currently working, i should clarify my first sentence in the last post..
i couldn't care less about the cosmetic look of a PRESSURIZED/EXPANDED tank"... a "blown up" tank is a bit misleading in the context of what I'm talking about about here ha ha i most certainly DO care a tank EXPLOSION!

I understood the meaning of "Blown Up" to mean EXPANDED. English is so much fun!

The argument may be made that there is no reason to vent the tank before use.
The pressure in the tank is the equivalent of pumping the primer bulb.
Tanks built today only vent IN to prevent tank collapse due to fuel use causing suction.
Hook it up and Go! Open the vent after the pressure is gone and the tank starts to collapse.

But otherwise, Yes, venting fumes into the boat is never a good thing.
Gas fumes are heavy and will sink into the bilge and tend to stay there.
As a compromise, if you insist on venting the tank, wait until you are on plane and there is a good breeze blowing though the boat.

Or vent the tank before you bring it aboard.
Starting with a full tank is always a good idea.
Filling it IN the boat is a very bad idea.

 

[luvmydixie]

Re: replacing plastic gas tank with metal

Have a 1986 Dixie Super Skier 299, anybody know capacity of fuel tank on this boat?

 

[emoney]

Re: replacing plastic gas tank with metal

Irish, as to venting the tank before starting an outboard and the concern of "fumes & spark", no need to worry there as the fumes aren't "trapped" as they are in closed type system, such as an I/O. I/O boats have blower motors because fuel is gas in both liquid and vapor form and can ignite of course. However, those systems have no "escape" for said fumes. In your Outboard's case, those fumes are immediately vented when they hit the air.

Something else to consider is with the new, post 2011 EPA rules, tanks, some of the older outboard require a pressure vent inline between the motor and the fuel tank. You know it's a "new" tank by the cap, as the new ones "click" as tightened, just like a lot of cars do. If your cap doesn't click, just tightens so far and then stops, then you don't have that type and need to open the vent to operate the motor. I don't believe your motor will run without the cap vented, btw.

 

[irish1985]

Re: replacing plastic gas tank with metal

Irish, as to venting the tank before starting an outboard and the concern of "fumes & spark", no need to worry there as the fumes aren't "trapped" as they are in closed type system, such as an I/O. I/O boats have blower motors because fuel is gas in both liquid and vapor form and can ignite of course. However, those systems have no "escape" for said fumes. In your Outboard's case, those fumes are immediately vented when they hit the air.

good to know, thanks!

Something else to consider is with the new, post 2011 EPA rules, tanks, some of the older outboard require a pressure vent inline between the motor and the fuel tank. You know it's a "new" tank by the cap, as the new ones "click" as tightened, just like a lot of cars do. If your cap doesn't click, just tightens so far and then stops, then you don't have that type and need to open the vent to operate the motor. I don't believe your motor will run without the cap vented, btw.

my cap doesn't click when i turn it. occasionally (maybe every time!) when i would forget to open the vent, it would stall out on me in the middle of the lake.. now i know why!

 

[Triton II]

Re: replacing plastic gas tank with metal

Hi luvmydixie. Please start your own thread to ask this question in the Dixie manufacturer forum here:

http://forums.iboats.com/Boats/Dixie

Good luck.

TII

 

[irish1985]

Re: replacing plastic gas tank with metal

what i've learned from this thread:

• i really don't need a metal can to replace my plastic one

• some people prefer to keep their vent open at all times

• some people prefer to keep their vent closed at all times (unless they're using the boat)

• those who keep their vent open aren't particularly worried about moisture leaking in or dangerous fumes leaking out.. those who DON'T vent while in storage ARE worried about these things

• those who prefer to keep their vent closed while in storage say that the tank expanding is not dangerous

like most things in life, multiple different answers for the same question... at least i am pretty confident that I don't need to replace my gas can

thanks all!