Series 81 fuel line mystery

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    Pierce-Arrow fuel lineHas anybody seen this sort of arrangement in a Series 81. The main fuel line goes from copper to rubber and back to copper. The branch takes off in copper where the rubber begins and feds back into the main line where the rubber ends. Both lines appear to carry fuel, and the valve doesn’t seem to make a difference in any position.


    Jack Davis


    Jack Davis


    That whole thing looks like a vapor lock waiting to happen. Unless it catches fire first.


    Is that an exhaust pipe directly below?

    Looks like one of Mr. Goldberg’s finest efforts.

    Someone went wild in the plumbing department at Home Depot.



    Looks like someone had a theory that they wanted to preheat the fuel, perhaps to improve vaporization in cold. Looks like it wouldn’t work well anyway, with no valve in the direct line and the heater line open the flow has to take two 90’s through tee fittings, so most of the flow is still going along the main. Just having the main fuel line paralleling in close proximity to the the exhaust pipe is a big vapor lock issue.


    Thanks to all for your thoughts.  Just to clarify, while the perspective in the photo makes it look like the fuel line is right on top of the exhaust pipe, in fact several inches separate the two, and there was a metal baffle or panel mounted between them that I have removed for cleaning.  I am thinking of simply taking out the copper bypass, and using the gap in the main line for installing an in-line fuel filter.  Several odd or unexplained things were done to this car over the years before it went into the museum around 1991, and this is one of them.


    I am wondering if there was an electric fuel pump plumbed in where the rubber hose is now.  Some electric pumps won’t allow the stock pump to pull fuel through them, consequently a valved bypass is put in. The bypass valve would be closed for times the electric pump was needed (priming or hot weather?).   I am not that familiar enough with the vacuum pump systems to know if this would work or not.  I have seen this type of setup where someone wanted an electric pump for occasional use. Is there any sign of mounting or wiring for an electric pump there? What is the red wire at the top of the photo? It looks like it has a wire nut on the end and doesn’t go anywhere, kind of hard to tell in the photo.

    I agree with Jim, it looks like a great setup for vapor lock and with any kind of a leak, a fire.



    An electric pump since removed does make more sense. The valve needing to be turned off manually when running on electric to prevent short circuiting.


    That’s why I had put in a diaphragm electric pump not a quieter turbine pump, the mechanical pump will draw through a diaphragm type. Jim L


    I believe you are all correct about the electric fuel pump.  I’ll look for signs of mounting or wire.  I do recall that when I got the car there were one or two wires running aft from the fuse box that weren’t connected to anything.


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