Fuel pump help, fuel pump pressure return Options

[porscheteck914]

Hi Fellows , I need some help /advice . 1973 914 1.7 with original Fuel Inj. Djet . Original 50 year old fuel pump -3 ports. When I go to start it , I have to bump the ignition switch 2 times to get it to start. Fuel pump runs . I have a fuel pressure gauge hooked up to drivers side fuel rail. Pressure goes to 36lbs when I turn on ign switch. When I turn off ign switch, pressure immediately drops to 0 psi. The real question is : Does the fuel system supposed to hold pressure or slowly leak down after ign switch is turned off ???? Does fuel pump have a pressure valve in its return to tank, to hold some pressure ? Do I need a new fuel pump ? thank you for any help . (IMG:style_emoticons/default/confused24.gif) Paul

[wonkipop]

the pressurized circuit after the pump and to the injectors should hold pressure.

i'd say the little rubber tip seal in the pump top port assembly is kaput.
instant bleed down.

everything you want to know about these pumps is here.
i have rebuilt mine.

http://www.914world.com/bbs2/index.php?showtopic=350416

but i do not know where you would get that little rubber tip seal that is inside the 3 port assembly at the top of the pump. fortunately that tip seal was good in the two pumps i fixed up.

i've tested mine since rebuild.
the bleed down on pressure is very slow when its like a proper functioning pump.
still holds pressure 24 hours later.
not at 28 lbs but its still got pressure.

35lbs is high.
prpbably been adjusted up the fuel pressure regulator to cope with bleed backwards at the fuel pump.

should be 28 as suggested by other posters for a D jet.