1989 Malibu question...

[2006RAMHEMI1979]

Hi Everyone,

I bought a 1989 Malibu 162. The problem I am having with the fuel tank. It has a built in tank and when it gets hot out it shoots gas out the back of the boat - not sure what it is called but it is some sort of breather. Is there a release valve or anything to stop this from happening. The only fix I have so far is to keep the fuel cap loose while it sits. When I unscrew the fuel cap, there is a lot of built up pressure.

Thanks in advance for any help.

 

[2006RAMHEMI1979]

Re: 1989 Malibu question...

Anyone?

 

[QC]

Re: 1989 Malibu question...

Does this only happen when the tank is full? If so, the only real solution is to not fill it so full. When any liquid warms it expands. Has to go somewhere, inside is bad, so it vents outside. That breather is the vent, it is required and there is no valving . . .

 

[2006RAMHEMI1979]

Re: 1989 Malibu question...

Thanks for the reply. No, it doesnt have to be full to do this, but I will try to keep it around half full and give that a try. Only problem being, she is a pig on gas and will be a short day without a full tank of fuel lol

 

[shrew]

Re: 1989 Malibu question...

Gas will definitely expand when heated. Gas is typically colder in the tank at teh gas station because the station tank is stored underground. The rule of thumb is to only fill your boat tank 90% to allow for some expansion. The tank should also have a vent tube which should allow for air to escape as the fuel expands when heated. There should be no pressure in the tank when the cap is opened. If you get a large amount of depressurization when you open the gas cap, I suspect that either the tank isn't vented properly or there might be a kink in the vent tube. More than likely what has happened it the expansion of fuel runs partially up the vent tube, which no longer allows air to escape the tank (there probably is no air in the tank anymore. Fuel has worked up the fill tube as a result of fuel expansion and the pressurization in fill tube is the remainder of air left in teh tank now compressed in the fill tube. the tank should never be so full as to begin filling the vent and fill tubes. It probably wasn't when you filled it, but beacause it was 'topped off" when heat began expanding the fuel there was no where for the fuel or air to go.

You stated: "when it gets hot out it shoots gas out the back of the boat - not sure what it is called but it is some sort of breather."

This sounds like the fuel is expanding so much it is coming right out of the vent tube. That would tell me that you filled the boat to 100%, then heat expanded the fuel and there was no where left to go but out the vent tube itself.

I would do the following:

1) Make sure the vent tube isn't kinked and venting properly
2) Don't fill the tank more than 90%.

 

[2006RAMHEMI1979]

Re: 1989 Malibu question...

Gas will definitely expand when heated. Gas is typically colder in the tank at teh gas station because the station tank is stored underground. The rule of thumb is to only fill your boat tank 90% to allow for some expansion. The tank should also have a vent tube which should allow for air to escape as the fuel expands when heated. There should be no pressure in the tank when the cap is opened. If you get a large amount of depressurization when you open the gas cap, I suspect that either the tank isn't vented properly or there might be a kink in the vent tube. More than likely what has happened it the expansion of fuel runs partially up the vent tube, which no longer allows air to escape the tank (there probably is no air in the tank anymore. Fuel has worked up the fill tube as a result of fuel expansion and the pressurization in fill tube is the remainder of air left in teh tank now compressed in the fill tube. the tank should never be so full as to begin filling the vent and fill tubes. It probably wasn't when you filled it, but beacause it was 'topped off" when heat began expanding the fuel there was no where for the fuel or air to go.

You stated: "when it gets hot out it shoots gas out the back of the boat - not sure what it is called but it is some sort of breather."

This sounds like the fuel is expanding so much it is coming right out of the vent tube. That would tell me that you filled the boat to 100%, then heat expanded the fuel and there was no where left to go but out the vent tube itself.

I would do the following:

1) Make sure the vent tube isn't kinked and venting properly
2) Don't fill the tank more than 90%.

Thanks a lot for the help. I will take a look at it today.