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Re: [T3] addendum to vapor lock question


On 18 Nov 2005 at 3:10, David Y wrote:

> 1) Vapor lock occurs at the fuel pump or before (i.e. on the input/inlet 
> side) therefore the position of the output hoses from the pump to the carbs 
> in relation to the engine block/heat sources is irrelevant... they can be 
> long enough to lay on the block itself and don't need to be 
> suspended/isolated (?)

That's correct. Vapor lock only occurs on the suction side of something, where 
the pressure/vacuum is low enough that the gas boils rather than being sucked 
forward.

> 2) A blockage in the lines/weak flow can cause the condition to occur, 

A blockage COULD CONCEIVEABLY cause a vapor lock, just by increasing the 
suction necessary to pull gas forward, thus increasing the likelyhood of 
boiling.

> Any suggestions beyond checking/cleaning that filter would be greatly 
> appreciated. 

Look at your car from the side. You'll see that in a type 3 the gas tank is 
actually slightly higher than the engine. It should take NO suction at all to 
pull gas to the rear of the car; it should flow on its own, especially if the 
tank is full. Try filling the tank; if the problem persists, you KNOW that 
vapor lock is NOT the problem.

Of course, if you always park nose downhill, this won't work.

> I have about 1/2 tank of gas right now. Any slick suggestions for cleaning 
> the filter without bathing in benzine?

Fill 'er up. See what happens.

Do you have the little anti syphon valve that VW supplied in some years?

Where is your filter located, before or after the fuel pump?

If the problem persists with a full tank, then I'd suspect a blockage somewhere 
(check this by just removing the hose from the pump inlet and seeing if gas 
flows out on its own) or a problem with the anti-syphon valve or the fuel pump 
or the float valves (very unlikely.)

-- 
Jim Adney
jadney@vwtype3.org
Madison, WI 53711-3054
USA

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