[T3] Fuel Primer Switch.....

[bobsnotch at aol.com]

I wonder if it has something to do with the check valve in the original fuel
pump. In the old days, you'd shut off the car, wait an hour and then re-prime
the system so it would be ready in the morning. However, it seems this doesn't
work anymore. Didn't Keith put in an external check valve on 1 of his cars? Did
that work Keith?

Turning the key on-off multiple times does work, but it also induces wear on the
switch (especially 1 year only switches like a 71 switch). Jim's solution is a
good easy quick fix, that really does help limit wear on parts that are becoming
obsolete. What people seem to keep forgetting is that the youngest of these
cars are 45 years old, and aren't getting any younger. The replacement parts
being made are not of the same build quality, and some just don't last.

An example of this could be the T-3 ignition switches used from 61 to 67 which
had a high failure rate (would literally fall apart), and they weren't asked to do what
the 68 on switches did. In their case (61-67), it was a bad design. Quite a few got
an aftermarket switch installed, because replacements weren't available.

Today's fuels are different from back then, or even 10 years ago. In the old days,
gas used to be red, now it's either clear or has a yellow tinge to it. I'm guessing
it's the additives that are in the fuel that don't make it burn like it used to.
Bob


-----Original Message-----
From: Jim Adney <jadney at vwtype3.org>
To: type3 <type3 at vwtype3.org>
Sent: Tue, Sep 25, 2018 9:39 am
Subject: Re: [T3] Fuel Primer Switch.....


On 25 Sep 2018 at 5:33, J. Jonik wrote:

> Why doesn't turning on the key multiple times, not to point of ignition, prime
> the fuel system?

Turning the key multiple times clearly works, but it adds wear to the
ignition switch. That's not as much of a problem on your '73 as it
would be on a '71, where a replacement switch is almost impossible to
find, but even replacing a '73 switch is much more work and more
expensive than a primer switch.

I think it's also likely that having a switch that allows you to run
the pump continuously, as opposed to a series of 1 second pulses, is
more effective in clearing the air out of the fuel system.

> Then, what's wrong that it NEEDS special priming tricks, or primer
> switches?Is there an old, worn out, or dirty Primer Switch somewhere that ought
> be replaced, or cleaned?

That's the $64k question. I don't know. I've worried about that for
decades and tried replacing everything in the system without
discovering the key.

The ONLY remaining suspect I have is the fact that when these systems
were new, all the fuel lines in the engine compartment had grey vinyl
covers over the gas lines. It's possible that this gave just enough
extra heat shielding that the heating/boiling problem didn't occur.

Over time, as we replaced those hoses, those sheaths were discarded,
because they were too hard to get over the new lines. Plus, most of
the time the new lines were larger than the OE so it would have been
impossible to slide the sheaths on.

It's also possible that this problem always occurred in our hotter
climates, and that it has gotten worse with global warming (yes, it's
real) and possible changes in the vapor pressure of modern gasolines.

I designed the primer switch kits to solve this very common problem
simply and cheaply. They're effective and cheap. They work.

--
*******************************
Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
*******************************

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