Starter Staying Engaged & Fuel Pump Constantly Running - '84 3.2

[mynameisjonas]

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I have a 1984 911 3.2 that I just picked up that the starter is staying engaged. I believe I have the problem narrowed down to the Yellow wire to the starter getting 12 volts as soon as the key is turned on. The car does not start until the key turns to the START position, but I feel the 12 volts to the starter terminal with the key on is keeping the starter engaged once started. Although I have gotten this far, I can't seem to track down the source. Any help troubleshooting would be much appreciated.*

Additional Info:
The car had been sitting in a garage for about 15 years when I bought it. I don't believe it had been started in those 15 years, so I took the precautionary measures before I tried to start the car - soaked the cylinders, turned over by hand, changed all of the fluids, flushed fuel system and replaced the gas tank. I also did a compression test and all cylinders came back within specs. There was an old alarm system in the car and not having a remote, I decided to remove the alarm system before I tried to start the car. Once the alarm was removed I tried to start the car and nothing. I was able to confirm the starter was getting power so I removed the starter and bench tested it to determine it was bad. Once I replaced the starter the car fired right up and sounded great, but it sounded like the starter was staying engaged. I removed the new starter to find it still engaged and showing a lot of heat/wear. First thought was bad rebuilt starter (Bosch), so I bought another one and replaced it. Here is where things don't add up! The new starter worked fine and no longer appeared to stay engaged. However, after a test drive I tried it again and then the problem came back. I also recalled that the fuel pump did not come on once I replaced the starter with the second starter in the On position, as it does now with the problem.

Here is what I have done/tested so far:
Test New Bosch Starter: Removed starter and disengaged it and then bench tested it (12V power to post and jump it to ignition terminal) and it works fine.
Tested Yellow Ignition Wire To Starter: Tested yellow wire to the starter and determined I have 12 volts at position one and two of the ignition. I understand I should only get 12 volts here when in the START position.*
Heard Fuel Pump Running/ DME Relay: I thought since the fuel pump is running on position two of the ignition switch and knowing it should not be, I thought to replace the DME relay as it also is related to the starter. Replaced and no change.*
Tested Yellow Wire For Continuity To DME: I tested the yellow wire to the starter back to the DME on pin #4 for continuity to eliminate any wiring modifications when the alarm was installed and it tested back to the DME just fine.
Replaced Ignition Switch - Still 12 volts to starter and fuel pump running at ON position.

This is as far as I have got. Any help to further diagnose would be appreciated!

[R2D2]

No idea if this helps but maybe the previous owner messed up the wiring to the back of the ignition switch or he messed up the yellow wire somewhere along the line (after market alarms often clumsily break into this yellow wire. The first can be checked easy enough. The main feed to the starter always has power so maybe there is a short somewhere along the yellow wire. I don't have a wiring diagram in front of me but IIRC the yellow wire receives power via the ignition switch which then in turn powers the starter solenoid. This wire goes via a number of connections along it merry way which makes it liable to develop bad connections over the years .  To rule this out you could try disconnecting the yellow wire ends from the ignition switch and solenoid. Then run a test wire from the yellow wire terminal on the ignition switch to the solenoid. 

[proporsche]

have a look at the ignition switch plug if somebody cut into the harness and lok there for a split on the yellow wire then let me know

 

Ivan

[johndglynn]

Also check the bakelite ignition switch itself. That is fairly notorious for falling to bits after reasonable mileage.