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RE: [T3] Fuel Problem

On 11 Nov 2003 at 10:27, Gamboa, Gary wrote:

> >Jim talked recently about installing a switch that
> >will run the fuel pump from the switch, so you can
> >pressurize the fuel ring before trying to start.
> I thought this was the cure for "heat soak". My issue
> is occurring when the car has been sitting all night.

It's really the same problem: The fuel boils away during the "heat soak", but 
then when the engine cools, air gets pulled back into the lines, rather than 
gas. When you try to start the car the lines are full of air. Even if the pump 
runs perfectly this air will just compress in front of the advancing fuel, and 
the car won't start on air, even 30 psi air.

The first thing you should do is get someone to listen to verify that the pump 
actually is buzzing under there for ~1 second every time you turn the key ON.

> Symtoms are different, when the car is hot, I get fuel,
> but its not enough to start the car; when cold, it just
> cranks, no fuel at all.

Assuming the air is the problem, which it probably is, the solution is to make 
the pump run enough to push all the air out of the lines. There are several 
possible ways to do this. You can crank the starter for a long time, since the 
pump runs all the time the starter runs, but this runs the battery down. You 
can turn the key ON and OFF a lot of times to accumulate a lot of ~1 second 
pumping times, or you can install the switch and just hold it down until you 
hear the air stop bubbling back up into the tank. This is rather simple to do, 
but it requires that you fabricate something.

Would it help if I just made up several of these switches? This seems to be 
coming up a lot lately and the old switch assy. from my recently scrapped out 
'72 is sitting on my dining room table right now. Perhaps I should just make a 
half dozen copies and offer them for sale. They would include all the wires, 
connectors, and brackets for you to just bolt them in place and wire them up.

Jim Adney
Madison, WI 53711-3054

List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org

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