The 2500S as sold in Australia and New Zealand has a non-vented fuel tank,
so the petrol cap is not the issue, in fact it must seal or else fuel will
spill, especially around right hand corners.
Like the American TR6's a carbon canister is in the engine bay which does
vent the tank and an antirun-on valve to dump the vacuum when the engine is
shut down. These are possiblities to check. There are the carburettors
themselves - these need to be properly tuned and has been mentioned the
ignition system needs to be thoroughly sorted and properly adjusted. Also
check the flexible pipe from the right hand side of the rocker cover to the
canister purge line (the larger pipe to the top of the canister) - if this
is blocked (and they do), the crankcase will develop positive pressure and
cause the symptoms described.
With respect to fuel delivery, pressure is not necessarily the issue - but
flow certainly is. If there are any blockages between the pump and
carburettors, no amount of pressure with deliver adequate fuel. This is not
a fuel injection setup where pressure is critcal, and if pressure is too
high, leakages will inevitably result. I suspect the fuel pump is OK.
In standard tune, the 2500S motor is not a high revving motor - the 5700 RPM
red-line is laughable. I found the fitment of a Pertronix kit did help in
achieving higher revs though.
With respect to the slipping overdrive - what grade and type of oil has been
installed in the gearbox?
David Greed
1974 Stag Man O/D
1979 2500S Man O/D
Email: Home: greed@wave.co.nz
Work: david.greed@telecom.co.nz
Webpages: http://www.wave.co.nz/pages/greed
.
----- Original Message -----
From: "jeffrey fenwick" <jfenwick@netcom.ca>
To: "Triumphs at AUTOX.net" <triumphs@autox.team.net>
Sent: Wednesday, 16 January 2002 5:04 PM
Subject: Re: Help needed with Fuel Pump pressure ??
> Any chance you recently changed the gas cap from vented to
> non-vented and the pump is sucking against the (almost) sealed tank?
> Right after the problem, stop,leave engine running and see if you have
> pulled a vacuum on the tank.
>
> Jeff
>
> Glen J. wrote (in part):
>
> > This is interesting. I have noticed that when the engine is colder
(after
> a
> > start or letting it sit for an hour or two then getting back in for
> another
> > drive) the slipping/starvation/timing problem is not present. After at
> least
> > 15-30 minutes of hard driving the problem returns.
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