[T3] Do you have a '68 or '70 Type 3?

[Jim Adney]

On 9 Jul 2016 at 17:04, Gary Forsmo wrote:

>    1. After my car has been sitting (for several days or weeks), about *how
>    long* should I "activate" the spring loaded fuel pump switch to fully
>    pressurize the fuel ring, before turning the Ignition Switch to start the
>    engine?

Whatever air/fumes gets in there will happen in the first few hours 
after shutdown. After that, any additional time will make very little 
difference. Whatever happens will depend completely on how hot the 
engine was when you last shut it off.

For example: Suppose you go out now, prime the system, start the car, 
and then let it run about 20 seconds, or just enough to get the idle 
smooth, then shut it off. Now the system is full and the engine is 
cold. Next time you start, you won't have to use the primer switch at 
all; just turn the key ON, wait for the pump to run for 1 second, 
then start. That works because the engine was shut down cold and 
full.

OTOH, if you drive to Madison, stop to fill up the gas, then get back 
in the car, there's probably been little time for the heat to soak 
into the gas lines and boil the gas. So you can probably prime it for 
5 seconds then start.

Finally, if you drive to Madison and then back home and park it hot, 
you'll want to prime it for 10-20 seconds the next morning.

>    2. Will I *hear* an audible change in the fuel pump motor when the fuel
>    ring is fully charged?

I don't think you'll hear any change in the sound of the pump. What 
you will hear at first will be just the sound of the pump running, 
then the sound of air/fume bubbling up in the gas tank, then nothing 
(meaning most of the air has cleared out of the fuel loop.) At some 
point there may be a sort of moan coming from the rear; that's the 
sound of bubbles coming thru the pressure regulator.

I usually try to start the car a few seconds after I stop hearing 
bubbles coming up in the gas tank. It probably won't start right 
instantly, because there will still be air in the injectors, because 
those are on side branches of the fuel ring, so they won't get swept 
completely free of air.

Your experience will be your best teacher. I find that 5-10 seconds 
is often enough. In Prescott, I sometimes did it for as long as 30 
seconds.

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