Re: [T3] addendum to vapor lock question

[David Y <goob@adelphia.net>]

At 08:31 PM 11/19/2005, Jim wrote:
> Okay, it sounds like you've got
> that part covered. I'll be interested 
> to see if the full tank "cures" your
> problem.

With a full tank, and now 100% new fuel hose all around, when the car is
on level ground gas will flow very weakly, but constantly out of the hose
at the engine side if I lower the hose to within a few inches from the
block. Is the flow of gas via gravity when the tank is full supposed to
be weak or a spurting, constant flow? 

To see if there were any obstructions in the metal tubing running through
the chassis, and without any compressed air (but with a relatively high
lung capacity ;) I blew into the line as hard and as long as I could from
the engine side, eventually hearing a bubbling coming from the tank. When
I released the pressure (i.e. quit blowing) a powerful rush of gas spurt
back through the line (glad I had a towel on hand and in place) before
the flow returned to the constant but weak dribble. If thew dribble is
normal, there is no obstruction in the lines from the tank to the fuel
pump, and the only heat source would be the single point where the line
touches the oil cooler tin in between the in-line filter and the fuel
pump, and I have this buffered with a piece of larger diameter hose. Thus
I could rule out vapor lock from overheated lines or/and or blocked
flow.

This leads back to the fuel pump. Yesterday when the condition occurred,
and I did the cold water trick, I heard a distinctive sucking/gurgling,
the in-line filter filled back up in a few seconds, and I was able to
start/drive immediately. The pump is probably 10-15 years old, and I
can't remember the last time I checked the internal filter (which must
mean it was 10+ years ago). Could it be that the pump has weakened for
whatever reason and does not create sufficient vacuum to overcome the
vaporization? A related question would be, if my engine is running at
180-190F, and the pump is mounted on the correct riser/block (there is a
1/2 or so in. non-metal riser under the pump) even with the post
shut-down heating of the engine compartment and components, would this be
hot enough to vaporize the gas in the fuel pump? If the answer is yes, I
would guess the pump is getting worn/weak, but then why does it run
strong at all other times? 

I'm starting to think it's an actual Gremlin! ;)

> I have some good used
> parts, including the nut, that you need. I 
> don't know if my gaskets are still good, but between the 2 of us, we
> ought to be able to come up with 2 good 
> gaskets.

That would be great. I'll email you to set it up. But regarding the
gasket, are you talking about the washer that sits on the output side of
the tube that contacts the nut? I was under the impression that the ring
of the screen served as a washer/buffer between the nut and
port?

My tank is the original stock 1968, with the extra small port to the
right of the large one with the nut. 

Thanks!

David Y.
68 Square



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