HELP! Engine starting Porblem!!!

[klober23]

After reinstalling my engine in my '76 912e I go to start it up it run for a sec then dies...I hear a sucking or blowing sound!?!?..I have checked all the hoses many times over and see nothing. Another problem I am having is one of my spark plugs keeps coming loose and now will not full get snug...it wiggles in place!?! What is wrong? Would this be the only reason my car will not start? How can I get the plug to tighten? Thanks

[WFBowen]

Can you remove the sparkplug? Do you know if anyone put in a heli-coil into the plug threads? Did it ever run off of idle? Triple check the vacuum line to the fuel pressure regulator. Was the sucking sound a constant or a "stroked" sound (i.e. combustion chamber - on/off?)
The airflow meter & just about everything else relies on a pre-determined vacuum level, so your loose plug could throw all that off, as the initial vacuum to the airflow flap sends a critical message to the computer to get everything going.