OT: 1973 911 CIS, Fuel check valve? Options

[benalishhero]

Good afternoon, can anyone familiar with CIS tell me where the fuel check valve is located? Does the system even use one?

Thanks

Thomas

[SLITS]

Cold start on CIS is a function of:

Control pressures regulated by the WUR ... cold, it drops the system pressure so the air flow plate rises more easily. Warm, it increases control pressure to lean out the mixture for hot running.

Air flow plate position ... must be centered and in the appropriate position in the funnel.

Mixture setting ... adjust one click at a time .. clockwise richer. It just adjusts the position of the metering barrel in the center of the fuel distributor.

Functional cold start valve ... don't know much about this.

The check valve in the pump is for hot starts. It maintains system pressure for about 20 mins after shutdown.

Yes, a WUR can fail both on vacuum (if yours has vacuum ports) and the heater element. The inlet port screen and outlet restrictor can plug from junk in the system .. rust, dirt, etc., If the heater element fails, car should run rich.

My 2.7L starts just fine, but I have it wired so I can turn the key on and let the pump build system pressure prior to starting. It needs to build a tad bit of heat before it will idle correctly (my cold start valve is disconnected and I have no AAR).

And the picture of the pump .... you are showing the inlet, not the discharge where the check valve is located.