Fuel Pressure Drops to zero the second the engine stops

[Sdubbya]

I have a 1992 325i vert. I bought it a month ago, had been sitting for years. I just finished rebuilding the head, replaced timing belt, gaskets, fuel pump, water pump. Everything seemed to be working ok, but suddenly it stopped idling. The car starts, but unless I give it some constant amount of throttle, it stalls out. I hooked up a pressure gauge using a T on the fuel line entering the fuel bar. When I jumper the fuel pump, I get about 32 psi of pressure. When I remove the jumper the pressure instantly drops to zero. I don’t see any gas leaks. Is it an FPR problem? Injectors? What would you screw with first?

[Sdubbya]

I ended up pulling the fuel pumps and replacing it and now I have the right fuel pressure and it holds its pressure. Frustrating considering it was a brand new Delphi fuel pump. At least it works now.

[Panici]

I ended up pulling the fuel pumps and replacing it and now I have the right fuel pressure and it holds its pressure. Frustrating considering it was a brand new Delphi fuel pump. At least it works now.

Thanks for the resolution update.

Do you think it was a faulty check valve in the new Delphi pump?

[hasa]

Faulty check valve would not stall engine. Would there be some fault in pump mechanical internals causing major internal leak or something.

[Sdubbya]

I was thinking maybe some kind of broken seal which would cause it to produce lower pressure and be unable to hold pressure. But I am not very familiar with the internal workings.