Boiling Fuel in the tank

[therhodesys Lurker Find all posts View Profile Close therhodesys]

Hi
I returned from a Simpson trip a moth ago and had the experience of the fuel boiling in the 4wd systems extended range tank. After a full day of driving in the heat (low 40's) the tank was so hot the petrol vapour was escaping the filler cap, no matter how hard I tightened it. When I undid the filler cap I had fuel spitting out the filler hole, such was the pressure in the tank (the vapour was escaping so fast the liquid fuel was being spat out too). I could leave the filler cap cracked open for 5 minutes and the pressure did not appear to reduce and when you listened it sounded like the fuel was boiling in the tank, bubbling noises.
I had a strong vapour smell in the engine bay too which was the exhaust pipe of the charcoal canister, you could see that vapour was also escaping through that.
It was like driving a time bomb.
This was the first hot trip with the new tank, it has been checked and all hoses etc are in place and not kinked.


My thought is that the excess fuel pumped to the engine and then returned to the tank ( I think the 97 3.4 v6 pumps more fuel than required and then returns the excess to the tank) was being heated along the way and thus heated the fuel in the tank ? The engine bay was hot, real hot, (one battery boiled dry) but the engine temp and auto oil temp remained in the acceptable range the whole time.

Has anyone else experienced this ?
Has anyone any idea what caused this ?

Thanks

Chris

[croozza Avid PP Poster! Find all posts View Profile Close croozza]

Fuel can not boil, it will evaporate, sounds like they have not set up the fuel tank correctly, cant really tell you what is wrong with it without looking at the setup though. But I am leaning towards a pressure build up.

[brogers Advanced Member Find all posts View Profile Close brogers]

Fuel can not boil, it will evaporate, sounds like they have not set up the fuel tank correctly, cant really tell you what is wrong with it without looking at the setup though. But I am leaning towards a pressure build up.

Petrol is a liquid hydrocaron obtained by fractional distallation, and it does indeed have a boiling point, it has a vapour point, a flash point, an autoignition point and many other propreties, including most definatly a boiling point,which is somewhere around 95 degrees celcius, The exact boiling point is dependant upon the exact constituants and additives and the pressure above the petrol itself. I'm not saying however that the petrol was actually boiling in the fuel tank, but something very strange was happening, maybe it was indeed boiling in the fuel lines and thus vapourising and bubbling the fuel in the tank etc...it must be investigated, I would be very concerned. I am sure there will be someone who who knows about this issue. Its makes me thankful I ahve a diesel I guess.

[ntp Addicted PP Member Find all posts View Profile Close ntp]

Petrol is a liquid hydrocaron obtained by fractional distallation, and it does indeed have a boiling point, it has a vapour point, a flash point, an autoignition point and many other propreties, including most definatly a boiling point,which is somewhere around 95 degrees celcius, The exact boiling point is dependant upon the exact constituants and additives and the pressure above the petrol itself. I'm not saying however that the petrol was actually boiling in the fuel tank, but something very strange was happening, maybe it was indeed boiling in the fuel lines and thus vapourising and bubbling the fuel in the tank etc...it must be investigated, I would be very concerned. I am sure there will be someone who who knows about this issue. Its makes me thankful I ahve a diesel I guess.

You had me at 'fractional distillation'.

[ntp Addicted PP Member Find all posts View Profile Close ntp]

I have seen this in Central Australia when people overfill fuel tanks (into the expansion areas). The fuel will properly expand, then evaporate, causing pressure & overflow.