Don't weld a tank if it's had fuel in it unless you can be sure of removing all traces of petrol/vapour. That is unless you like loud noises and rearranged body parts.
Hi All,
Iwas going down to Stonleigh at the weekend end, after 100 miles the engine died. When I pull the petrol cap off it was a massive effort. The was
some fuel in bu t put some petrol in anyway a few turn overs and it started again. Now coming home, got to Birmingham and it died again, this time I
knew that I filled up in Cov so it wasnt fuel. is the fuel cap suppose to be a massive effort to get off or is the tank making lots of pressure, sort
of sucking the cap on hard. it seems to be presurising not releasing air. I may be wrong but have any of you guys had this. is there a solution.
Its an MK Alloy tank with Areo filler.
Cheers
John
[Edited on 7/5/04 by j30fos]
I bought an MK tank at the show and now I look at it I'm not sure how you avoid the problem, it sounds like you're getting a vacuum in the
tank.
Are you using a feed and return set-up or feed only?
Maybe you could fit a breather with a filter to the return pipe on the tank if you're not using it.
be sure to post the solution when you find it!
Cheers
Nick
you are not replacing the fuel with air resulting in the fuel starvation. opening the tank lets the pressure equalise and bob your uncle. Perhaps a tiny hole drilled in the cap would be the solution.
Hi John
Sounds like you havent got a tank breather. A few guys I know who have an aero cap have drilled a small 1.5/2.0 mm hole in their fuel cap just under
the latch Cheap, quick and easy fix.
Alternative is to put a T piece in the filler neck and a one way flapper valve.
Cheers
Jim
You need a vent. Either a vented filler cap or a vent on the tank. Easiest way would be to weld a small piece of tube onto the tank (assuming its aluminium) and drill a small hole through into tank. Then stick a rubber tube onto pipe with a return to stop any crap getting into tank.
quote:
Originally posted by Hellfire
You need a vent. Either a vented filler cap or a vent on the tank. Easiest way would be to weld a small piece of tube onto the tank (assuming its aluminium) and drill a small hole through into tank. Then stick a rubber tube onto pipe with a return to stop any crap getting into tank.
Don't weld a tank if it's had fuel in it unless you can be sure of removing all traces of petrol/vapour.
That is unless you like loud noises and rearranged body parts.
As britishtrident quite rightly states, you'd need to make sure its totally de-gassed first.
Thought that might have been quite obvious - but maybe not - in which case, also, don't forget to drain the fuel into a suitable container in a
safe manner, then uncouple it from the fuel lines and remove it from the boot area of your indy and get it totally de-gassed before attempting to do
any welding near it.
Probably still summat else I've missed..............
jon says you can drill it and use a bicycle tyre valve to let air in. works for him, though i have never done it myself.
john i will send you the same thing i used to do mine with when i send you that cable
Lads what way do you modify the car tyre valve to do the job. david
Just to complicate things - regarding the cycle valve.
On a hot day the petrol and gases expand... quite substantially. Where does this extra volume of matter go if in a closed - one-way - system?
The vent is designed to let air IN not out...
I actually had a thought - could you not use something like what is now regularly seen on shower wash caps - basically a piece of rubber or semi-solid
flexible diaphram and cut a very fine slot in it. That way if gases expand it'll escape under pressure - if it contracts (or gets used up) is
will allow gasses the other way - vacuum. NO?
Just a simple thought! 
put 2 cycle valves in, one each way round. not sure what pressure they open at but it would only allow this much either side of atmospheric pressure
then. no mods needed, just screw/stick it in.
I can't help thinking we're reinventing the wheel here. Surely Caterham, Tiger, Westfield etc have all had and solved this problem.......
of course I don't know how they solved it
Fixed and sorted :-) al I did was drill 6 small holes under the flap next to the key in the aero filler cap. Now when the cap is undone there is now
air realease, simple mod, best thing is its not visable because the key cover flap is covering them.
Cheers for the responces
John
[Edited on 18/5/04 by j30fos]
Westfield fit a small valve inthe top corner as you can see in the picture. Yes it is my car so no-one take the p*ss because its not a locost.
[Edited on 18/5/04 by tony9876]
Sorry to be thick- where's the picture?
Cheers,
James
It's a secret
Think the file was too big actually will try again tomorrow.If it helps its a little red non return valve in the corner of the tank .