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Clayso, Master Automobile Technician
Category: Dodge
Satisfied Customers: 880
Experience:  ASE Master Certified Automobile Technician. 30 Years Experience.
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I have one injector firing not both, 1991 van 350, ughhhh...

Customer Question

i have one injector firing not both
JA: What is the model/year of your Dodge?
Customer: 1991 van 350
JA: Are you fixing your vehicle yourself? What have you tried so far?
Customer: ughhhh... replacing injector replacing pcm
JA: Anything else you want the mechanic to know before I connect you?
Customer: checking wiring no
JA: Have you checked all the fuses? Do you have a wiring diagram?
Customer: yes and yes
Submitted: 11 months ago.
Category: Dodge
Expert:  Clayso replied 11 months ago.

Hi There,
This is Clay, I'm a certified master automobile technician with 30 years of automotive repair and diagnostic experience.

From your description I'd say there is a wiring problem to the injectors. The DG/BK wire is power from the ASD relay to the PCM, coil positive and to both of the injectors. There should be power during cranking. At the injectors, the WT/DB and the Tan should pulse ground with a test light clipped to the battery positive. I understand that one of the injectors works properly. Check the other and let me know if there is power missing or the pulse to ground.

If there is no pulse to ground check the injector's circuit at pin #16 for injector #1 WT/DB and pin #15 injector #2 Tan at the PCM. If there is injector pulse at the PCM and not at the injector simply run a new wire to the injector from the PCM.

I hope this information is helpful. If you have any questions let me know. Also if you need a connector view with the injector pin locations let me know. You can reply back to me through this thread at any time.

Let me know

Customer: replied 11 months ago.
I checked the wire at the pcm and also had the same voltage. bought a new pcm because I thought it would be the board and same thing happens.
Expert:  Clayso replied 11 months ago.

Thanks for getting back to me. It's not voltage you're looking for at the PCM. You need a ground pulse from the PCM to turn the ground on and off at the injector.

With a TEST LIGHT clipped to battery positive probe pins 15 & 16 at the PCM. With the engine spinning over or running. Does the test light flash on and off on?

This is the proper way to check or injector pulse.

Let me know

Expert:  Clayso replied 11 months ago.

This is with the PCM connector plugged in and checking the wires at WT/DB pin 16 and Tan for pin 15 for injector pulse.

The DG/BK wires at the injectors should have constant battery voltage during cranking and engine running.

Hope this helps, let me know.