Mechanical Injection RPM Transducer Problem

[LEO73T]

Thanks to all who answered my previous questions!

My 73 911T is backfiring and running poorly. In the course of sorting out the various potential problems such as linkage, timing, valve adjustment, and dwell; I came across an article about how to test the transducer.

It said, hook a test light to the micro-switch (previously checked to be OK) the other end to ground. The book said the light should come on at 1300 rpm and go back off 1700 rpm. I can not detect any power at any time going to the switch.
The middle fuse in the back is working.

The book says the transducer is a dealer repair item. Does anyone have experience with repairing a transducer? I would be greatly appreciative of any idea.
Leo 910-471-1696

[Flieger]

Just hold the throttle cross-shaft open to 3000 rpm with your hand and depress the microswitch, if the system works the revs will cut out and drop down towards idle, then come back up and bounce between 1500 and 1300 rpm.

Here is how to repair the speed switch transducer: For MFI Gurus. . .and friends of Warren . . .