1973 Porsche 1.7 D-Jet, No power to two injectors Options

[crodog]

I have power to #3 and #4 injectors but not #1 and #2. The car will run but it is missing on 1 & 2. I have spark but when I pull the wires off the injectors nothing happens. After testing more I found I have no power to both of them. Where does the power come from? Do I need to look at the releasing contacts at the base of the distributor?

[JeffBowlsby]

Actually the injector groups as the ECU see them are:
1&4, 2&3, diagonally across the engine. Their shared transistor would only see a 1 fuel injector load at a time when one of them fires as controlled by the trigger points, making most efficient use of that transistor, but the ECUs rarely are a problem.

Injector pairs 1&2 and 3&4 share a common ground.

So depending on which pairs of injectors goes down, suggests a look at either the grounds or trigger points.

[larss]

Actually the injector groups as the ECU see them are:
1&4, 2&3, diagonally across the engine. Their shared transistor would only see a 1 fuel injector load at a time when one of them fires as controlled by the trigger points, making most efficient use of that transistor, but the ECUs rarely are a problem.
.....

Just curious how that could work since each injector in a pair is electrically tied to the other (only a 6 ohm resistor divides them)? I can not see the triggers, as how they are connected to the circuit, being able to divide the signal to reach just one of the injectors in a pair.

My theory is that both injectors in a pair are activated at the same time and this is not optimal since they not ignite at the same time - a compromise. They have chosen the pair 1-4 and not 1-3 since 1-4 are closer in the fireing order (1-4-3-2) making it a better compromise.

Pls correct me if Im wrong!

/Lars S