1983 928 fuel injectors no ground signal

[dzie]

I have a 1983 928S Porsche that would start but not stay running, I replaced the HL- injector relay XV1 & fuel pump relay XV11. It than ran for a short period of time, now it will not start. I now have 12v to each side of the injectors leads & no ground pulse. the new fuel pump relay now tests defective, the original was 92861511301 the replacement was not. I have a new one on order.

I am running into some issues attempting to check the system out.

Issue #1: The multi pin connector on the jet control unit under the right side
of the dash has 27 pins not 35 like many show to test.
I need a identification for each of the 27 pin connectors.
I need the logic & test procedure for the injectors, both hot & ground sides.

Issue #2: where is the transistor ignition unit located?

Issue #3: Where is plug X of central electric board?

Issue #4: I need logic/flow from the green wire via distributor.

Issue #5: I cannot find the ground under the dash for the panel/control unit etc.

I am getting a pulse on the green wire plug when I crank it over.

I also cleaned the fuel tank & cleaned & tested all of the injectors.
New fuel pump & filter.

Does this 1983 928S only have one control unit (27 pin)?

[stepson]

Grounds are located on the passenger side cam covers (brown wires with bolts into the cam covers)
Computer grounds are located in the passenger footwell above the Central fuse panel.

Normally, the L-Jet computer is very stable and is not the normal cause of failure, however IIRC the ground for the injector relay gets that ground through the L-Jet computer. At least in the later cars, the lack of that ground is a beginning stage of that computer failure. I don't know that to be the case for the L-jet, but you might keep it in mind and test the L-Jet by asking a friend to install your L-Jet computer into their running car to test it.