gas tank / fuel tank collapsing under vacuum pressure

[Super_Surf]

2003 Supra Launch

-gas tank is being "sucked" inward with vacuum pressure, causing top of gas tank to be very concave

-there does not appear to be a dedicated vent line to allow air in when fuel is consumed

-gas cap is a replacement by previous owner and is air tight


How is the gas tank vented on this model of boat? Should it have a vented gas cap to allow air in when fuel is consumed? Am I not observing a dedicated vent line somewhere that could be clogged? We inspected the gas tank all around looking for something like that but can only determine this set up may need a vented gas cap?

Thanks in advance!

[csuggs]

I would think there has to be a vent somewhere. Not sure about a 2003, but I would look for the external part of the vent somewhere on your boat, then "backtrack" to the tank. There should be a hose connecting the two.

[Super_Surf]

Great idea, and that's what my father in law(custom car builder), brother in law(mechanical engineer for volvo) and me (barely know where to put oil) have done. They had the seat out and the top access panel looking for some type of vent and they were not able to find one. They're convinced this thing needs a vented fuel cap although all the owners manual does not say anything about that nor do the pictures in the owners manual look like it has a vented cap. Thanks for the reply! I may try and call Supra today, I've never called them before. It'll be interesting to see if they are willing to answer questions like this.


Thanks!

[csuggs]

It sure sounds like you've done the right things. I didn't know that Supra used a vented fuel cap, but maybe on the later models they did. We both know it has to be vented and if there is no other vent on the tank, it has to vent through the cap. I'll bet Skier's Choice will be able to fix you up!

[Super_Surf]

I called Supra and they said all boats since 2002 come with a vented gas cap. The previous owner put a non-vented gas cap on as a replacement and thats why vacuum pressure was collapsing the fuel tank. No air could get in to displace the fuel that was being consumed! Thanks for the replies!

[Super_Surf]

By the way the Supra technical support was very helpful and glad to answer my questions over the phone. Excellent service!