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I have been getting air pressure in my fuel tank. Enough pressure to expand the tank. When I remove fuel filler cap lots of air escapes and you can hear the metal from the tank returning back to its shape. I have a return type fuel injection system on my 61. I also have a vented cap. Not sure why my tank builds up with pressure?
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My 64 Galaxie had the same problem. The gas cap is designed to let air in but not out. I modified the gas cap valve spring so if the tank built up a little pressure it would let some out. The cap I used was a Motorad MGC-40 Fuel Cap.
Last edited by JWSpeed (September 10, 2017 6:53 am)
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I'm curious to know what modification you made to gas cap. Even more curious to know why pressure builds in fuel tank?
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My tank in my 61 Sunliner also builds pressure with a vented cap. It is a replacement tank that did not have a vent tube like the original.
I just found a Spectra tank that has the vent tube and they are under 200.00.
Mike
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dan_6776 wrote:
I'm curious to know what modification you made to gas cap. Even more curious to know why pressure builds in fuel tank?
Fuel evapourates and seems to expand with heat. Do you have a Jerry can with gas for a lawnmower? Does it blow up like a balloon when it sits, especially in the heat, and hiss when you open the cap? With all the heat we've had this summer, and your new system, it is not surprising that you may have some issues getting these things sorted out.
I've heard of guys just drilling a hole in the fuel cap to provide two way venting. It would be nice to get the details from JWSpeed as to what modifications he made. I'm sure it could be helpful to many.
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I tried to modify a Gates cap by drilling a small hole in it. The problem with that was if the tank was over half full, gas would leak out. The Motorad MGC-40 Fuel Cap has a valve that can be removed by bending a couple metal tabs. I removed some of the spring until there was just enough tension to barely keep the valve closed. This allows the valve to open if the tank build just a slight amount of pressure.
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Thanks for the replies...JWspeed, I will check out my cap and see if I have any options for venting
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