Tank pressure?

[Ara]

Guys,

I had the ignition go bad on my '07 ST. The mechanic changed the tank key. Now when I open the tank to put in gas, there is no pressure. Before the change there was a lot of pressure.
What is normal?
Also, the dealer claims the locks for the 2 cases can not be changed and that Triumph says they won't replace them. I'll have to use the old key for the cases and the new key for the ignition, tank, and glove box.
I'll be calling Triumph NA tomorrow about this.

Ara

[ This message was edited by: Ara on 2007-05-24 01:22 ]

[NikosR]

No vacuum in the tank is the correct thing to have. When you open the tank cap you shouldn't hear a hiss as air enters the tank.

[ This message was edited by: NikosR on 2007-05-24 00:16 ]

[Ara]

The service manager claims they fixed some vacuum hose because of pressure building in the tank.
I'm asking because at this point I don't really trust them.

Ara

[NikosR]

Pressure never builds in the tank. If vacuum hose or tank cap is bad, vacuum builds up as the gas level lowers.

[Ara]

Nikos,
So no pressure is normal?
I wonder why the tank had lots of pressure yet worked fine for the last 4200 miles.

Ara

[steventhechef]

Nikos is correct. There should be no pressure in the tank

[NikosR]

Let me rephrase:

1. There should be no pressure difference between open air and tank

2. If things are faulty, the thing that can happen is external pressure gets greater than tank pressure (i.e. tank starts building a vacuum). Result might be fuel pump can pump the fuel efficiently.

3. There can't be (to my knowledge) a case where air pressure is lower than tank pressure (i.e. pressure builds in the tank).

Hope it's clear and please anybody correct me if I'm wrong.

[Simmo]

The problem will have been the tank vent being blocked or kinked in the past and fixed by the mechanic. As you ride the temp. causes a pressure build up. Not good. Keep a check on the two pipes fitted below. One vents the area around the filler, a water drain, the other is the tank vent that passes through a filter thingy on the way out. Take care to ensure that the tank vent pipe extends below the fairing. Fuel that escpaes will melt the plastics.
Cheers, Simmo

[clockwatcher]

I'm not sure about the '06 version, but my 2000 has a vent line with a plastic check valve located on the right side of the tank near the fuel pump housing. The valve MUST be routed in a vertical position or it will not allow the tank to vent properly. The valve is designed to prevent fuel from dumping out in case of a cash which, of course, could cause the bike to catch fire. I used to have pressure problems too. So much that it caused the sending unit to leak. The valve is very sensitive. If it is set vertically, maybe spray some light oil into it so that works properly.

[Ara]

Thanks guys.
It's scary and yet interesting to me that the bike has been fine for 4000 miles with pressure building in the tank.
I'll locate these hoses and make sure their OK.

Ara