Forgetting to open vent on portable tank

[BugsBunnyBoater]

Will forgetting to open the vent on my portable cause the motor not to run?

 

[Bart Sr.]

Re: Forgetting to open vent on portable tank

Not right away but as fuel is pumped out a vacuum builds impeding the flow.

 

[5150abf]

Re: Forgetting to open vent on portable tank

I second that Bart.

I leave mine cracked a little all the time because here in Indiana we have such a wide swing in temps, it can be 50 in the morning and 80 in the afternoon which causes alot of pressure to build up in the tank.

 

[fishrdan]

Re: Forgetting to open vent on portable tank

^^ x3

I leave mine cracked because of temp swings too,,, and also elevation swings driving to the lake.

Drove from 1000-9000' one time with it sealed and it almost looked like a watermelon, well not really, but you get the picture Plus, if the tank is pressurized, so it the line and connector,,,, and the connector won't pass gas (that doesn't sound right) because the pin is jammed hard against the seal, too much pressure to unseat it when plugging it into the outboard, have to unseat it with a screwdriver, fuel spraying everywhere...

 

[gss036]

Re: Forgetting to open vent on portable tank

^^^X4.

 

[Woodnaut]

Re: Forgetting to open vent on portable tank

As Bart said, they will run for a while then there will be too much of a vacuum in the tank for the fuel pump to draw any more out. Open the vent, squeeze the bulb a few times and its off you go.

The last time I did this, it ran just long enough for me to get across the bay and into the Intercoastal. Right amongst the barge traffic. Idiot. I made a quick recovery, but that pretty much cured me for life.

 

[cribber]

Re: Forgetting to open vent on portable tank

Make it part of your launch routine... Straps off check, plug in check, pop open vent check... and then anything else you do.

 

[rebars1]

Re: Forgetting to open vent on portable tank

Definitely need to open the vent! My son came in once after forgetting to open the vent and the 12 gal plastic tank was sucked down on itself to about half it's size! I don't know how the motor kept running. A local boat mechanic told me that people usually just make it to the harbor entrance and can't figure out why their motor suddenly stopped running.

 

[snodgrass.zach]

Re: Forgetting to open vent on portable tank

wow maybe this is my problem too(not letting the gas tank breath) lol but wont it loose the prime when u open it???? if its 90 degress out side and u have it closed would it cause the motor to flood????

 

[Home Cookin']

Re: Forgetting to open vent on portable tank

It won't affect the prime.
I think the vent should be open a little all the time except transporting. Be careful leaving the vent open as you can get rain water in.
Due to the ethanol issue, try not to leave your tanks in the sun when not in use. In the old days they could sit in the boat all summer; no more.

 

[tx1961whaler]

Re: Forgetting to open vent on portable tank

wow maybe this is my problem too(not letting the gas tank breath) lol but wont it loose the prime when u open it???? if its 90 degress out side and u have it closed would it cause the motor to flood????

The vent needs to be open when the engine is running; the fuel system is designed that way. If the float and needle jet are working correctly, it should not flood.

 

[Mark42]

Re: Forgetting to open vent on portable tank

Forgot to open the vent on a 6 gallon portable tank connected to a 40 hp Evenrude. After a few hours, the motor started to run badly. I stopped to check it out and noticed the primer bulb was sucked flat, then noticed the tank had the sides sucked in and the top was collapsing due to the vacuum pulled on the tank. Try crushing one of those tanks down with your bare hands, or feet even. Thats one great fuel pump in those Evinrudes!