Fuel on roof. Fore or aft?

[alanymarce]

@alanymarce, The fumes are only an issue if you have a leaky can and no sense of smell. Now I know it depends on your vehicle but I am pretty sure it would take a hell of lot of gas on a hot day to reach a dangerous concentration, as in ignitable. Both the Canada Safety council and the fire dept are going to go with absolute safety. But I use 20 L no vent cans and carry inside where the removed right side passenger seats were, and I have never had an issue leaks or fumes. I do inspect the gasket every time I fill and carry a spare set.

Generally I know exactly how far my Discovery II will go on a tank of gas, and on any trip more than a day I carry at least 20 L as a backup.

Like most I prefer that weight down low

Yes you're right that it's good to keep the CoG low - we need extra fuel so rarely that we drive to the circumstances and transfer the fuel as soon as we can. We've had to carry extra fuel, as far as I recall, three times in the last 149,000 Km, so this is not a big issue (actually a lot further than that, since in daily travel we never carry extra fuel). The only place where we carried extra fuel routinely was in the Congo, over a couple of years, and even then only when heading out of town.

The issue with fumes is not ignition, it's the effect on the driver. I agree with you that it's only going to be a problem with a leaky tank, although recall that when temperature goes up (vehicle sitting in hot sun while parked during the day for example) the fuel and vapour expand and there's not much you can do about it. If you then want to drive off and find there's fuel vapour in the car, apart from its being unpleasant, you'll probably have to drive the first few Km to ventilate the interior of the vehicle, which may not be ideal in 40 deg C or rain. Good seals will help. Certainly sounds as if you've got it under control.

 

[rgallant]

@alanymarce the point below is very good, when it get hot up here at lunch I pop the gas can out and vent it, then do that same at dinner. I usually only have to do it the 1st day. Being up in British Columbia, and on the coast we do not get that many days a year that it is a problem.

although recall that when temperature goes up (vehicle sitting in hot sun while parked during the day for example) the fuel and vapour expand and there's not much you can do about it. If you then want to drive off and find there's fuel vapour in the car, apart from its being unpleasant, you'll probably have to drive the first few Km to ventilate the interior of the vehicle, which may not be ideal in 40 deg C or rain. Good seals will help. Certainly sounds as if you've got it under control.