Paul,
re:
"Is it normal practice to fit pipes to the vents on a BJ8?"
According to (at least) one SU fuel pump book I have read there should
be flexible tubing from the unvalved vent at the diaphragm end of the
pump body. The flexible tubing should be routed to a clean, dry
location. AFAIK, Healeys were never fitted with such vent tubing
(surprised Burlen didn't know this). I installed one to vent in the
boot.
Sometimes, there's a cylindrical plastic cover on the check valve. It
doesn't come with new pumps, however.
re:
"I called Burlen UK who make the pumps and they had not heard of this
problem before but assumed that the pump was creating excess pressure
from within and was expressing it through the valves."
I don't buy this explanation. The valves are one-way to either draw
fuel into the pump or expel it to the carburettors--there should be
little, if any, air passing through them unless there are leaks in the
system (or the tank is empty). The pressure created is limited by the
strength of the spring behind the diaphragm (SU fuel pumps should
produce about 3psi, give or take). Excess pressure usually results in
flooding at the carbs.
bs
Paul Baker wrote:
I thought you might be interested in an update on this after I have
had a chance to do some investigation.
It would appear that air is escaping or being released from either
the vent at the plastic housing end or at the metal body end. It is
difficult to work out from which it is coming as its very intermittant
and with the noise of the engine.
I called Burlen UK who make the pumps and they had not heard of this
problem before but assumed that the pump was creating excess pressure
from within and was expressing it through the valves. Their view was
that if the pump was not leaking and working fine then it should be
ok. They were surprised that as the pump is mounted under the rear
seats that neither of the two vents had pipes leading rearwards from
the pump as they felt that water could get into the pump through the
vents and be causing this problem. As I said before, the pump has
been on the car since 1991 when the car was rebuilt and has not caused
any problems. Is it normal practice to fit pipes to the vents on a
BJ8?
As I have a new SU electronic pump which I had kept as a spare, I will
put that on the car and keep the old one as the spare. It will be
interesting to see if this one, plus vent pipes, makes the same
noises.
Paul
67 BJ8
66 BJ8
65 Sprite
*******************************************************************
Bob Spidell San Jose, CA bspidell@comcast.net
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