fuel tank overflow

[nofish95]

I have a '94 trophy, center console, with a 30 gallon fuel tank. Prior to my last fill up the fuel gauge was registering nearly empty. I took the boat and pumped in 9.5 gallons of gas when the pump cut off(but this is another issue). I took the boat home and mixed in the appropiate amount of 2 cycle oil and covered her up for the weekend. Now 2 weeks later the temp. has changed about 30 degrees, from 35 to approx. 60, and the fuel is spewing out of the fuel cap.<br />Is this because of the temp. change and maybe some trapped air???.<br />I have had the boat for little over a year and this is the first time this has happened in the winter.<br />I have had to siphon out about 2.5 gallons of mix to stop the overflow, i'm hoping this has fixed the problem.<br />Anybody with any ideas and more knowledge????, I sure need some help on this one. <br /><br />Thanks,<br />Nofish95

 

[snapperbait]

Re: fuel tank overflow

You may have a blockage in the fuel tank vent... The change in temp would cause pressure (trapped air) to build in the tank which is why the tank has a vent to relieve the pressure...

 

[nofish95]

Re: fuel tank overflow

much grass, I'll check it out, thanks for the reply.<br />Y'all keep'em straight down there<br />Nofish95

 

[Solittle]

Re: fuel tank overflow

If you have a 30 gallon tank registering empty and put 9.5 gal in it before shutoff you need a new sending unit for your fuel tank. Happened to me a couple of months ago.

 

[62_Kiwi]

Re: fuel tank overflow

Hi Nofish95<br /><br />I get the same problem with my boat if I leave it with a full tank of gas. When the boat gets hot in the sun, the gasoline expands and spews out the breather hole.<br /><br />For this reason I like to leave filling up the tank until I'm on my way to the water. Storing the boat without a full tank of gas is the answer.<br /><br />The other advantage of this, is that your fuel will be fresher when you're out on the water - and there's less chance of forgetting whether your tank is full or not.

 

[nofish95]

Re: fuel tank overflow

Just wanted to say thanks to all who replied. I'll have to do some work on this fuel tank.<br />I'm thinking if the vent pipe is clogged, that would give erronious readings to the sending unit,(trapped air and all).<br />Thanks again<br />Nofish95

 

[Solittle]

Re: fuel tank overflow

Don't think the vent pipe has anything to do with the sending unit for the fuel guage. The sending unit has a cork or other floating device that floats on top of the fuel and is connected by a wire or rod to a reostat. The level of the fuel will result in the correct electrical pulse being sent to the fuel guage (same principle if not an electrical guage). The problem occurs when crud gets into the reostat. Pressure in the tank (your theory from a clogged vent pipe) should have no effect on the sending unit. <br /><br />Anyway - good luck and let us know the result.

 

[nofish95]

Re: fuel tank overflow

If there is no place for the gas vapor to vent would it not build pressure in the tank, causing the liquid to compact?????.........<br />Too much theory, simple problem. need fix.<br />thanks

 

[masterp]

Re: fuel tank overflow

Air is easily compressed not fuel. Automotive gas tanks actually have "air bladder" expansion tanks to deal with this. I have to agree with SoLittle. The fuel spilling, and gauge problems, are two diferent issues. Just because something isn't probable doesn't mean it's not possible!

 

[Boatist]

Re: fuel tank overflow

nofish95<br />I have a question first, Is your fuel vent higher than your gas cap?? If it is higher then may not be plugged at all. If lower you need to check the screen.<br />To start with I would replace your Gas Cap O RING there cheap, it should not leak fuel. It is a safety problem but also if gas leaks out water can get in.<br />Second I would compare your mechanical fuel gauge to the electrical one. If they read the same but do not match your actual fuel level then you porbably have a mechanical problem. If Mechanical one ok and electrial Wrong I would check sending wire and ground wire on tank and guage. Make sure they are clean and tight. If wires are ok then can be the guage, some can be adjusted or the reostat / sending unit in tank is bad.<br />Pressure causeing wrong level is not possible. You can compress air but not liquid (gas, water).<br />Let us know what you find.

 

[nofish95]

Re: fuel tank overflow

Guess I have lots to do.<br />Thanks again to eveyone