my project wellcraft 180 fisherman

If when not using the boat the vent should be closed, but on a hot day will expand. But if it rains water can get in the vent so I use to leave it open all the time and just cover the tank with a small tarp I had when at rest.
 
mannydvk11 said:
really good answer thank you very much now my other Q? after that answer is if i keep it open will gas evaporate and give me water problem in my tank o will water come in the tank trow the vent also if the tank is collapse will the motor have a problem like if is running with out gas o will it prevent the gas to circulate when is collapse

https://www.youtube.com/watch?v=ewXwbDiYacM here is a link on how the gray valve is suppose to do but am not sure if this is for my motor
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Okay, one at a time...

1) If you open the vent then yes, a very tiny portion of gas will evaporate over time. Since your gas is inside an enclosed container, the only place for it to go is either out the fuel line to the engine, or (as a vapor) a tiny amount out the vent on your gas cap. The hole in the vent is very small, and only allows for expansion or contraction at a slow rate. Just enough to equalize the inside and outside pressures. As you run your engine and it pulls fuel from the tank zero gas vapor escapes from the vent. But once the engine is stopped and the gas inside starts to expand then a tiny amount of gas vapor will escape. So yes, you will lose a minuscule amount, but insignificant in the overall scheme of things.

2) No, you will not get any significant water into your tank by allowing the vent to be open during operation of your boat. Just screw the vent closed at the end of the days run. In a much larger tank, where the gas sits for days or weeks at a time, and there is not way to close the vent, then yes, due to first expansion of the gas during the warm day and then contraction of the gas during the cooler night, a small amount of water, in the form of humidity in the air will enter the tank and then condense into water as it cools. That's one of the reasons why we have fuel/water separators on the fuel line(s) going to the engine. If you still have a fear of water entering your engine from the tank, just empty whatever is left in it at the end of the day into your lawn mower. string trimmer, auto, whatever, and start out with a fresh tank of gas on your next time out on the water.

3) Yes, if the vent is closed, then your engine will create a vacuum in the tank as it pulls fuel from it. That vacuum will eventually become so strong that either the engine will stall out because it can no longer overcome the vacuum and receive gas, or, the plastic tank will collapse from the greater (14.7 lbs psig at sea level) atmospheric pressure being exerted on the outside of the tank.

Remember....NO manufacturer is going to add anything extra to a product if it isn't needed.... that costs money and will eat into their profit. So in the case of your plastic gas tank, the vent that is added into the gas cap costs the maker extra money and would not be there if it were not needed. Use it, it's there for a reason.
 
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thanks you very much Destroyer i was wondering about that because i saw that happen to me yesterday when i took the boat out for a run and the gas tank was collapse and the engine was turning off at hi rpms
 
Mannydvk11, I did a little research and found out what that grey thing is. As I suspected, it's a pressure regulation device. It's called a "Fuel Demand Valve". You can find out all about it at the following link:

http://www.mercurymarine.com/parts-and-accessories/product-overview/portable-fuel-system/

Please notice that in the description it clearly states that it's to prevent fuel from a pressurized tank entering an engine and creating a fire hazard. What isn't stated is that the pressurized tank is being mandated by the EPA (Extremely Pathetic A$$holes) to prevent fuel vapor from entering the atmosphere. (Even though pressurized tanks create a fire hazard). In other words, it's something that we could have lived without but is being forced down our throats by an overzealous government agency. So instead of the simple, cheap two-way vent (a sealable hole) that used to be on portable tanks, now there's an expensive one way valve that only allows air into the tank, but will not release vapor out, (thereby causing the tank to become pressurized as the warmed fuel expands) and a fuel demand valve system. And of course, it ain't free. If anyone has noticed the outrageous price of portable plastic gas tanks lately it's because they all must use a special plastic now so that Ethanol doesn't effect them. Just another little cost/tax being forced on us by big brother. But I digress... the grey thing is as I described it previously, a safety device.
 
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Have you thought about installing a Moeller Marine fuel tank? I am planning on replacing my old tank with one of these. Since the original is untreated aluminum, and for what ever reason that Wellcraft decided to foam the tank in causing the tank to corrode even faster.

Here are the links:

http://www.moellermarine.com/oem/fuel_tanks/fuel-tanks/

Do you have the measurements on yours? I have a 1990 Fish 18 and I was told it has a 50 gallon tank.
 
Starzofchaos said:
Have you thought about installing a Moeller Marine fuel tank? I am planning on replacing my old tank with one of these. Since the original is untreated aluminum, and for what ever reason that Wellcraft decided to foam the tank in causing the tank to corrode even faster.

Here are the links:

http://www.moellermarine.com/oem/fuel_tanks/fuel-tanks/

Do you have the measurements on yours? I have a 1990 Fish 18 and I was told it has a 50 gallon tank.
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sorry i have not answer for some time but yes now am looking to see how to repair the problem i do use the regular outside tank for now works OK for now

i have taken out the boat a few time after fixing the reebs and rebuilding the carbs no problems yet by the way the t-top is holding strong i really like it. i add it a all around light you can see it on the pic

here are some pics





 
New windshield

i was looking to buy the windshield but i know how to work acrylic my friend gave me this small peace of acrylic so i made my windshield :sun:









 
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