Take a light tester and go to the starter solenoid
On a 75 there are two prongs sometimes these get mixed up when they are reconnected
One will give voltage on start and one will give voltage all the time when key is place in the run
(Don’t forget the old run/start thing. that is in the Chevy world if a car starts and runs and you release the key and shuts off then the start/run wires are hooked up backwards)
Back to Opel EFI
Pwr for the EFI system comes from the starter relay (the starter solenoid has two prongs)
pwr from one prong of the starter solinoid should come on and stay on after the car starts (light tester can be a big help)
If it passes that test you move on to the dual relay
It’s been years and years since I played around with one
But this might help (pg 21)
http://www.texas912.org/912E%20T...l%20Manual.pdf
before i found out you could go down to a bug shop and buy a dual relay i would have to take my dual relay apart and jumper some wires out to get the car to run
*note--AFM (air flow meter AKA flapper meter) -- MAF (Mass Air Flow AKA Hot wire) the Opel does not have a MAF meter
The AFM has a switch in it to control the fuel pump but this functions after the car comes off the start circuit
Or in other words the fuel pump will run one way on the start circuit and through the AFM switch on the run circuit
It is assumed once the car is running and on the run circuit air going through the AFM and will keep the fuel pump activated
Hope that makes sense but the wire diagram on pg 21 shows how it works sort of
If the car wrecks and no air flow is going through the AFM and even if the key is still on the fuel pump is shut off
So in other words it’s a safety device
Those are the first initial check I would make
After that you your back to the basic L-Jetronic troubleshooting
The dual relay does fail a lot
I can go on to the other stuff if you want
HTH
Davegt27