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On 19 Nov 2005 at 21:07, David Y wrote: > 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? I would not expect the flow to be particularly strong, because the "head" is small and it's a long line (lots of resistance to flow.) I suggest that you also do this test with the gas cap off, just to make sure that there is not a second problem with the gas tank vent line. > 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. When you blew bubbles into the tank, you pressurized it a bit. This would cause the initial burst of flow. If the vent line isn't working, once the pressure is gone, you might get a bit of suction which might retard the flow, even if it wasn't enough to hear when you open the cap. > 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. There's also your extra oil cooler above the transmission. That may add heat to the line, as well as to the transmission. It's worth thinking about.... (Herb's Law of Unintended Consequences) > 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? I doubt if it's anythink like a "weakness" in the pump. If it's a pump flaw, then I'd suspect a bit of dirt in one of the valves, which is something that can be cleaned out. > 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? Judging from the microfilm, you're right. I must have remembered it wrong, but I haven't looked at my actual parts. > My tank is the original stock 1968, with the extra small port to the > right of the large one with the nut. Yes, that was the return port for the FI. -- ******************************* Jim Adney, jadney@vwtype3.org Madison, Wisconsin, USA ******************************* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~