Aux tank fuel eruption

[airbur]

At the gas station filling up the other day....I removed the aux tank gas cap and a bunch of it regurgitated all over me and the side of the Bronco. I imagine this was caused by the differential in pressure....does this mean the new gas caps I bought from the local auto parts shop aren't vented?

 

[Explorer]

Gotta get 10 letters, new cap not vented.

 

[blubuckaroo]

At the gas station filling up the other day....I removed the aux tank gas cap and a bunch of it regurgitated all over me and the side of the Bronco. I imagine this was caused by the differential in pressure....does this mean the new gas caps I bought from the local auto parts shop aren't vented?

No, a vented cap will still hold pressure in the tank. It has a check valve that lets it draw in air.

 

[broncnaz]

X2 vented caps let air in not out. but there are some that work both ways. I guess you figured out that your aux tank was full and didnt need filling

 

[airbur]

It was a pretty hot day..not sure if that had anything to do with it. Should I replace the caps? Maybe I filled it too high previously?

 

[blubuckaroo]

It was a pretty hot day..not sure if that had anything to do with it. Should I replace the caps? Maybe I filled it too high previously?

Read the answers. They have check valves and only vent in.%)

 

[73azbronco]

your vent to charcoal canister is not working.

 

[airbur]

your vent to charcoal canister is not working.

So what is it that I need to do? Replace something?

 

[Justafordguy]

You will just need to figure out why it's not venting. It must be stopped up somewhere. Probably one of the hoses.

 

[taipeichris]

Hi,

My main and reserve tank do this too.

Gasoline expands on hot days. If you over fill the tanks or top them off at night or on a cold day, then just "park it" without driving it, when the sun hits it the gas will expand "burping" your tank.

My 66 has a new metal main and a new reserve tank with no charcole canisters, new gas caps too.

My answer is don't top it off!

BUT if you see gas leaking from the filler tube on a hot day, grab a funnel, a gas can, and get ready to catch!

I measured it once on my main tank, it' was only about 12oz. I'm fine with it but my neighbors are afraid of it and my girl hates it when I smell like gasoline.

Good luck and I hope you don't smoke!
Chris

 

[DirtDonk]

Yeah, the smell can be annoying to friends and family. For some reason though, we seem immune to it's effects.

What they said. You can check your vents with some compressed air airbur. Do you have a compressor handy? See if you can remove the small vent tubes and gently blow air through not only the tubes, but back into the tank (cap off of course) through the small nipples.
Your '70 should, I think, have two vent lines on the main tank, and one on the auxiliary. Does yours have the plastic condensing tank behind the driver's shoulder, under a panel in the cab? If so, then yours should have the lines I mentioned. If not, then there may be a variation, but I think your '70 should still have had a charcoal canister under the passenger side fender well mounted to the frame.

Check those things out at least and see what results you get.

Good luck. It may be something you just have to live with, but if it's a clogged vent line, it'll make your life easier in the future. In the meantime, to as Chris says and don't fill it all the way. Your Aux tank should hold about 7 gallons normally? Or can you get more in there?

Paul