My wife's '91 740 non turbo, 250+K miles has an intermittent hard start condition cold. The engine cranks, fuel pumps operate, the thing fires on one or two cylinders as it cranks but it takes forever for the others to chime in and the thing to start. Once it starts there seems to be a brief cloud of gassy smoke, then the thing settles down & idles and runs fine. No restart troubles after it sits for a while once it's been started for the day. So far it has not failed to start, just takes a lot of cranking some mornings. But not always.

Ignition components have been replaced in recent history; no vaccuum leaks near as I can tell; I haven't checked the fuel pressure but I'd think if the pressure were bleeding off due to a leaky check valve, none of the cylinders would fire until the pressure got pumped back up. Any thoughts?

Nick