[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [New Search]

Re: [T3] Update on fuel pump adjustment

I've just searched the Type 3 and the combined K(fuel system) manual to find the
reference I was sure was there, and I can't find it.  I was also reading through
the carb pages, and I think I've maybe mixed it up in my mind with the twin-carb
accelerator pump adjustment procedure, which involves changing spring tension
with different thickness washers.    DOH!

The Type 3 manual does describe adjusting the diaphragm spring coil-spacing to
change the pressure, and also advises that the push-rod stroke changes the
pressure.  I remember years ago there was a run on the flange gaskets as people
were told they could reduce fuel consumption by putting an extra gasket or two
under the pump.

The extract reads:-
"The pump pressure is determined by the adjustment of the push-rod stroke and
the diaphragm spring tension.
The push-rod stroke is adjusted by adding or removing flange gaskets.  ...  If
the push-rod adjustment does not give the desired result replace the diaphragm
spring.  Otherwise, if the pump pressure is too high, the intermediate turns of
the spring may be coiled closer together, and if the pump pressure is too low
they may be stretched apart."

I suspect the push-rod stroke wouldn't do much to make a Type 1 pump give the
right output pressure for a Type 3, though the opposite might be true.

Incidentally, the 1965 manual mentions 4.5 psi, so maybe it was increased to 5
psi for the 1600.

The washer (was it 1.5mm?) added by Ben gave an extra 2psi ISTR.

Some people have reported using a Type 1 pump without any apparent problems.  If
you get problems, I can't see a washer to increase the tension enough could do
any harm.

VW also say that under normal operating situations the diaphragm moves only a
fraction of a millimetre.

UK VW Type 3 & 4 Club

To unsubscribe, E-mail to: <type3-off@vwtype3.org>
For more help, see http://vwtype3.org/list/

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [New Search]