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Triumph TR6 - Petrol tank breather

Hi All
I have an ex USA TR6 which has had all the emissions kit removed, there is a breather from the petrol tank neck which terminates adjacent to the rear NS shock absorber and this seems to be causing a smell of petrol in the garage when I open after several hours. Does anyone know where this should go in the absence of the emissions kit? Is it actually needed?
r algie

Hi Ron

Yes its needed otherwise the tank would wind up having a vaccum as gas was used.

It went to a Carbon canister at the front. That had a purge line into the carb.

Make sure you vent the garage well before you start car. You should either get a canister of some sort or have some type of 1 way valve. Those fumes are explosive.

Bill Brayford

Is vacuum in the gas tank common? What kind of problem would result if there was? How can this be checked even with a seemingly functioning carbon canister?

Why does the car stall if the air intake to the canister is blocked with your finger?

A lot of questions, I know, but I am curious as may relate to current problems I am having with my 76 TR6.

C Wiebe

Hi Chris

If the tank has a full or partial block of incoming air or atmosphere to be technical. The fuel being sucked out by the pump creates a vacuum in the tank. As it increases the fuel pump starves the carbs. Intermittent stalling, cutout, rough running, bogging. Vacuum takes awhile to build and a very short time to go away when suction is off in a clogged system.

The tank vent line runs around the trunk and to the canister original. Can become kinked blocked, bugs, rust plugged fittings etc. Restricting flow air flow causing vacuum in tank..

Yes quite common for stored cars. Leave the gas cap part open to test for the lines and tank. If its a tank vac. problem it should go away.

Bad fuel line rusted and filter from tank to pump can do the same.

Your 76 has a canister with an anti run on electrical switch that closes purged tank air and fumes off from the carb to prevent Dieseling. When ignition is off. Putting your finger over intake at bottom does the same running at idle?

All your idle air is coming from the canister tank? I have never worked on those emissions or taken a 76 canister apart so I don't know how that set up works.

You know from other posts you have a problem with temperature and or time. Temp. should only affect emmisions I think. Time running that could be a vacuum build? Or both as things tend to expand with heat?

Sorry Chris hope some of the other fellas with 76s have a more specific answer on the canister tank.

The other item not to overlook is exhaust restrictions. Once had a tech. instructor that pointed out to the class the only perfect vacuum is in Bills head. Bill and a couple of buddies placed some nice garlic cloves and some steel wool well up his mustang exhaust pipes shortly after. First the car only smelled rotten. After the steel wool rusted plus flakey soggy garlic 2 weeks passed it ran rotten to:) He was quick only took him 3 weeks to figure out and about a minute to blame me. Fast friends for life but he always refered to me as that A**H*** don't no why.:)


Bill Brayford

Hi Bill
Thanks for the reply, the smell of petrol isn,t as bad as that and it dissipates quite quickly when the garage doors are opened. Have you any suggestions what to do with the breather in absence of the carbon canister [long gone],does anyone know how the injection cars are vented in absence of the canister or is it a sealed system due to it recirculating?
r algie

This thread was discussed between 17/05/2003 and 20/05/2003

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