AO

Go to 928GT.com and print out the fuel and relay chart for the car.

I agree with Sean that it could be a bad LH. However, the only thing that I know will cut the fuel pump and the injectors is a bad Crank position sensor. Sometime the connectors can be gnarly and you can accidentally plug them in backwards.

But there are three other relays to check before digging into that stuff again.

These can all be swapped with the horn relay to verify they are working.

Ignition Relay - X
LH Relay - XXV
Fuel Pump Relay - XXVI

One other possibility is the Kick-down relay (if the car is an automatic) can interupt the injector pulse but wouldn't affect the fuel pump - XVII

Mrmerlin

you need to verify that you have the crank position sender wires correctly connected,
could they be swapped with either one of the knock sensors or the TPS sensor.
Do the relay swap after verifying the connectors

dcrasta

Do you have power at all ? (I always suspect the ignition switch .. sorry.. biased)

AO

The EZK does not control injectors.

LH = Fuel control / injectors
EZK = spark / ignition timing

Mrmerlin

CPS turns on the LH and EZK.
if its not connected to the correct plug the car wont run.

Also if the tach, isnt getting a signal from the CE panel the car wont run

Verify connectors then replace.......the relays listed, ... one at a time,
then try to start after each swap out, (this will isolate the bad relay)

XXVI LH jet Fuel injection # 53 Then

XXI Ignition System its a (# 53 with a fuse tester) Then

XX Fuel pump # 53 Then

X Ignition relay # 53,,

note PN for the #53 relay is 141.951.253.B
you can use the horn relay to verify if the relay position is working, its a #53

Smell the old relays for burning or melted solder joints where the pins come out of the bottom of the relays,
any corroded pins or burned relays should be opened.

MAKE sure to also replace the fuel pump fuse

See if the tach is jumping when you crank??
yes then the CPS is working though the signal may be weak.

Fuse relay chart here.
https://www.928gt.com/skin2.htm

John Speake

Use Andrew's info and also this - http://www.jdsporsche.com/fault%20find.html

CPS feeds engine rpm to EZK, you should have spark if EZK relay and EZK are good. If you have spark, then tach should flicker when you crank the engine.

EZK feeds modified engine rpm info to pin 1 LH ECU. Unless LH gets this signal, it will not energise the Fuel pump relay or fire the injectors.

So if you have 12v rpm signals at pin 1 LH and the LH relay is good, there is the possibility of a dead LH ECU.

Mrmerlin

nice link John