90 740 Cranks but won't start (intermittent)

[bigb1rd]

Hi, I've been troubleshooting this for about 3 weeks now. My'90 740 16valve intermittently won't start. I "know" it's a fuel injection problem because the car will start immediately when I spray starter fluid in the intake hose. Using Forum resources & help I have replaced the Fuel Injection Relay (the big white one), swapped the Radio Interference Relay with the Aux. Fan relay, replaced the speed (crank) sensor, and replaced the in-line fuel check valve. When it won't start I have tapped on the ignition module & listened for the fuel pumps which are working. I thought it might be the "cold start valve" but can't find one on this car. I'm out of ideas.... any suggestions? It seems to start good for a while after disconnecting the battery cables to "reset" everything, but then starts NOT STARTING AGAIN (unless I spray it with starter fluid)! Any Ideas Appreciated,
Thanks,
Dirk[b][/b]