[T3] fuel pump problems

[Jim Adney]

On 9 Oct 2013 at 17:40, Gary Forsmo wrote:

> I took the '69 Square out for an "exercise run" today.

> 1)  I wanted to fill the fuel tank with "fresh" 91 octane. ("pure gas", no
> ethanol @ $3.75.9 per gallon)
> The fuel gauge said: 1/4 full.  I pumped 9.447 gallons.  Le Yikes!
> Either the gas gauge or the sender is "sticking".  I think it may be the
> dash instrument.

Seems odd, unless this is something it always did. I'm hard pressed 
to come up with an explanation for why it should start to do this 
suddenly.

> 2)  I wanted a full fuel tank to prevent (as much as possible) fuel tank
> "breathing" of moist ambient air and introducing moisture into the tank and
> fuel system.

That's exactly the right thing to do. I will add that it's probably 
best to come back to the car and start it again once the engine has 
cooled down completely. The object is to fill the fuel loop with gas. 
If you shut down with a hot engine, the heat soak after shutdown will 
boil off all the fuel in the lines and leave the injectors dry. It's 
best if they are left wet.

> Question:
> IF ... moisture from ambient air gets into the fuel tank which is not
> sufficiently full, and the water settles in the lowest area of the fuel
> tank, when you drive the car for a 50- to-75 mile trip, does the water get
> A.)  pumped through the fuel ring, injectors? or

Some will. Whatever gets to the injectors will get injected along 
with the gas and get "burned." If it's just a small amount, you'll 
never notice it.

> C.)  something else?

Water in the gas will eventually get sucked into the fuel loop. Small 
amounts will be caught in the paper filter element and won't 
circulate. A little alcohol in the gas (Heet or ethanol) will take 
this into solution and let it pass. Water that gets thru the filter 
will either be in solution and be recirculated or "burned," or it 
will be churned into very small droplets by the pump and the same 
things will happen. 

> 3)  Since the car will "go to sleep" in an unheated airplane hanger in
> Wisconsin for 6 months or so, I ALWAYS put the appropriate quantity of
> PRI-G (trade name)

I've stored cars for years with no special treatment at all, other 
than topping the tank. This has always worked just fine for me.

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