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Re: [T3] addendum to vapor lock question

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.


David Y.
68 Square
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