Fuel injector voltages

[Shadow]

I'm having some problems getting the '87 4cyl to start. It turns, it sparks,
it gets fuel to the brand new injector, and there is 3 volts of power to the
injector while the key is in the ON position. The power does not pulse when
the engine is cranking, and it does not spray fuel. As the injector is brand
new, I doubt it's that.
Does anyone know what the injector power connector should read during
cranking? 12 volts? More? Less?
What could cause it to not get the pulse signal on a DIS engine?

[R W Hughes]

There are two teminals on the injector, one should read battery voltage
all the time, the other will read battery voltage when the key is on and
the engine not running and a variable lower voltage when the engine is
running.

[Shadow]

Well, I tried the voltages on the injector. Both the red and blue wires were
tested against ground dead when the car off.
When the key is ON, the red wire reads 12v, the blue wire shows nothing.
When the key is cranking, the red still reads 12v, the blue wire, still
reads nothing.
When I tested the blue against the POSITIVE, it showed negative voltage.
I swapped the meter leads, red to battery + and black to the blue wire.
It showed 3 volts while ON, and it fluctuated as the engine was cranked.
Any ideas? It doesn't match what R W had posted so I'm wondering what could
cause strange behaviour like that.

Post by R W Hughes
There are two teminals on the injector, one should read battery voltage
all the time, the other will read battery voltage when the key is on and
the engine not running and a variable lower voltage when the engine is
running.
--
Robert W. Hughes (Bob)
BackYard Engineering
29:40.237N, 95:28.726W or perhaps 30:55.265N, 95:20.590W
Houston, Texas "The city with too much Oxygen"

[Phil Randolph]

In the Fiero injector system there is a always hot wire going to the
injector and the ECM grounds the other wire to fire the injector

Post by Shadow
Well, I tried the voltages on the injector. Both the red and blue wires were
tested against ground dead when the car off.
When the key is ON, the red wire reads 12v, the blue wire shows nothing.
When the key is cranking, the red still reads 12v, the blue wire, still
reads nothing.
When I tested the blue against the POSITIVE, it showed negative voltage.
I swapped the meter leads, red to battery + and black to the blue wire.
It showed 3 volts while ON, and it fluctuated as the engine was cranked.
Any ideas? It doesn't match what R W had posted so I'm wondering what could
cause strange behaviour like that.

Post by R W Hughes
There are two teminals on the injector, one should read battery voltage
all the time, the other will read battery voltage when the key is on and
the engine not running and a variable lower voltage when the engine is
running.
--
Robert W. Hughes (Bob)
BackYard Engineering
29:40.237N, 95:28.726W or perhaps 30:55.265N, 95:20.590W
Houston, Texas "The city with too much Oxygen"

[R W Hughes]

Check the injector with an ohmmeter, this sounds like it is open.

Post by Shadow
Well, I tried the voltages on the injector. Both the red and blue wires were
tested against ground dead when the car off.
When the key is ON, the red wire reads 12v, the blue wire shows nothing.
When the key is cranking, the red still reads 12v, the blue wire, still
reads nothing.
When I tested the blue against the POSITIVE, it showed negative voltage.
I swapped the meter leads, red to battery + and black to the blue wire.
It showed 3 volts while ON, and it fluctuated as the engine was cranked.
Any ideas? It doesn't match what R W had posted so I'm wondering what could
cause strange behaviour like that.

Post by R W Hughes
There are two teminals on the injector, one should read battery voltage
all the time, the other will read battery voltage when the key is on and
the engine not running and a variable lower voltage when the engine is
running.
--
Robert W. Hughes (Bob)
BackYard Engineering
29:40.237N, 95:28.726W or perhaps 30:55.265N, 95:20.590W
Houston, Texas "The city with too much Oxygen"