Success!!
I am declaring a great victory in solving my cold-start problem.
Recap: Originally, I was focused on the cold start solenoid on top of the fuel console but I’ve been informed by the experts here that this solenoid doesn’t function until temperatures drop to 14 degrees F (who the hell drives an MFI car in 14 degree weather??). I will ignore this little solenoid for the rest of my life.
I then turned my attention to the cold start system mounted directly on the MFI pump. Following Ed Mayo’s guidance, I tested various fuses, wires, relays, thermo-time switches…all checked out fine (as described earlier).
Yesterday Ed suggested that I see if the cold start solenoid on the MFI pump clicks when connected directly to 12 V…it does.
He also said to use a test light to see if the gray wire to the solenoid temporarily transmits 12V during engine cranking…it does.
This battery of tests tells me that the MFI’s cold start mechanism is functioning normally.
So, why the cold start problem?
It finally dawned on me that something else must be out of spec. I then replaced the sparkplugs, which were sooty. I also replaced the points, rotor and distributor cap. I tested all of the ignition wires for resistance and continuity and found that the #5 wire was completely dead (obviously it was the plug connector that failed since the wire is solid). Seeing that, I then replaced all wires with a fresh set of Beru wires.
[Public Service Announcement: I previously replaced the fuel filter with a cheap-o unit that I bought from a large parts-house online at about half the cost of a Porsche filter. When it was pressurized it leaked like a sieve through a poorly crimped seam. This could have burned down my car, garage and house! Only buy genuine Porsche fuel filters.]
Having checked or replaced all vital components I took a deep breath and turned the ignition key…the car started right up!
Lesson learned: before delving into the complex MFI system, make sure everything else is in good working order. Check your fuel quality & quantity, fuel filter, plugs, points, wires, cap, fuses, relays, switches, etc.
Just remember: any problems you’re having with your early 911 have already been experienced and solved by someone on this Forum. Don’t be afraid to ask for help…that’s how we learn from one another.
A special thanks to Ed Mayo for guiding me through this…I now have a pretty good understanding of how the cold start system works.
Thanks for following along.
Time for a bone-dry Martini!
Alan
N.J.