Been overseas on a project for a while - on the return the cold start injector wasn't working properly on my old 911 Porsche "Frau Helga" which made it virtually impossible to start in cold weather. Naturally the accessible wiring and thermal control switch checked out fine which meant that the cold start valve located way down low between the back of the intake manifold and fire wall was probably the issue. The Chief German Engineer-in-charge must have been on vacation for some rookie to decide where to mount this thing.
I found that I could just touch the dead cold start valve for removal using both hands once the front tires were removed (just kidding) - upper flexible rubber intake boot, air filter, blower motor, other misc stuff were removed. After a day of soaking it in an industrial strength diesel injector cleaning solution, the intermittent solenoid plunger portion of the cold start valve slowly began to click with +12 vdc applied. The final issue turned out to be that the fuel nozzle tip was obstructed internally. Using the stripped center wire of a twist tie I worked on the outlet tip gently until it was open. The small inlet thimble fuel screen was carefully removed to be cleaned and inspected using a long sheet metal screw. The upper inlet port side of the injector can now be easily filled with cleaner and forced through using air pressure to make sure any internal contaminants are removed. I then tightly wired an old tire air valve with the center removed to seal over the cold start valve outlet tip. At this point I used a handheld "pulsed fuel injector tester" to repeatedly chatter the solenoid coil while injector cleaning solution was blown through the internals using an air nozzle in both directions.
Once the small inner thimble filter was back in place, another soak or two in the industrial cleaner and then few more cleaning blasts of air pressure - I had the cold start valve showing a nice fuel pattern and working like new. The final step was a closed pressure test using the air nozzle-compressor set to 100 psi to make sure there was not any fuel leaks through the cold start valve when NOT ENERGIZED.....
Good Luck - Michael
