Thursday, 26 February 2009

Fuel Filler Revisited

Time to revisit the fuel filler. After using TFE hoses between the tank / filter / pump / bulkhead to avoid the smell of petrol guess what?....... my boot smells of petrol! It is more of an aroma than a smell but nonetheless it has started to annoy me.

After several days sniffing / venting / sniffing again it I have narrowed it down to the flexible filler pipe. This is a flouroelastomer lined silicone hose. It is fuel proof but not necessarily impermeable to fuel vapour. The impermeability of the hose is a function of the concentration of the flouroelestomer applied to the inside of the hose and the general method of application and by the sound sof it some variation in impermeability should be expected.

There are some hoses that are more vapour proof but these tend to have a spiral wire reinforcement - this can make it difficult to get a good seal. GD normally fit a vent pipe to the tank. I didn't as I had a Vented Cap. However upon investigation the vent in the Aston filler cap need a fair bit of pressure to open the rubber flap. This is OK for preventing the tank becomming pressurised due to heat or preventing a vacuum as fuel is used up, but it will allow fumes to build up inside the filler hose.

So time to fit the vent like I should have done in the first place! The vent is a simple affair with a 1/8 NPTF fitting tapped into the filler neck:This fitting incorporates a compression fitting to take a length of brake pipe:This runs down the inside of the boot and out through the boot floor via a couple of grommets and some sikaflex:

The filler hose was re-fitted with plenty of blue hylomar and the carpets stuck back down. Only problem now is that the boot smells of evo-stik at the minute... which is remarkably like petrol!!

So time will tell...... fingers crossed.

I've added some more jobs to the snagging list!! nothing major, mainly some SVA compliance checks that I need reminding to do.