Accepted Answer

Possibly cold start valve or thermo switch not working. (Left side of the engine, by the intake manifold)

The fuel distributor unit may also be adjusted too lean.
Lifting the valve plate manually with the ignition turned on, will squirt fuel into the cylinders and act as a primer.

A bit less common cause would be an airflow plate (the valve mentioned above) travel stop adjusted wrong. There is a stop screw for it on the air cleaner box side that can be used to adjust the rest height of the plate. If it's adjusted too low, you would not get enough fuel through to start.

Also look for air leaks. The intake manifold pipes have several rubber sleeves under the airbox that can deteriorate with time and start leaking, causing a lean condition. Very hard to get to, and therefore often ignored.

But wait, there's more! The CIS injection air boxes are vulnerable to backfires, and the box may crack as a result, causing a massive intake air leak and lean condition. Many vehicles have already been fitted with a pop-off valve in the air box, on the left side.. in case of a backfire, the valve relieves pressure from the vulnerable bottom half of the box into the upper half, keeping the box from splitting. The box may be fine, but the valve could be leaking. See that it's sealing properly, the spring is intact etc... and the epoxy used to seal it in place is still holding.

http://www.pelicanparts.com/techarticles/911_pop_off_valve/911_pop_off_valve.htm

Expert:	Jan Andersson
Pos. Feedback:	100.0 %
Accepts:
Answered:	7/25/2009

ASE Master Tech

20 years of automotive repair & modification, USA, Asian, Euro, old & new cars.