I have a 1995 Dodge Dakota V6 3.9 L automatic with 120,000 miles. What would cause my number six fuel Injector harness to stay on(open), causing fuel injector to spray gas constantly, while engine is running?

Several possibilities.

I'd first rent a NOID light set from a big box auto parts store (AutoZone, O'Reilly, and Advance Auto Parts around here all have tool rental plans) and see if the ECU is commanding it to be on, or if it's mechanically stuck.

After that, it's easier to figure up what's broken.

Aside: My 1988's ECU decided to NOT fire one of my two throttle body injectors, and it's a moderately common failure on some MN12 Fords (1994 Thunderbird and/or Cougar with 4.6L V6's IIRC) to have the drivers short. Both were easy to figure out with the NOID light, not so easy without *grins*

RwP

Thanks for responding. I did a noid light test and on the #6 cyl the noid light stays on. I replaced the computer but it still has the problem. What's weird is if I disconnect the connector in the middle of the wire coming from the alt. to the ASD box, it runs fine. The check engine light goes off and truck runs smooth.....but engine won't keep my battery charged.

Huh. At this point, it's time to check the factory service manual and see how they interrelate (the ASD/alternator wire and the #6 injector). Could be a shorted wire in the harness? So, the NOID light blinks on #6 if the ASD/alternator wire is disconnected?

RwP

Yes, the number 6 cyl blinks with noid light plugged in and alt. wire disconnected. I did also fix the factory splices under asd box, but I will double check them. How would I start troubleshooting that section?

Take the wiring diagrams in the factory service manual, and start tracing what you have in relation to what it says you should have.

I'd also "run the wiring harness" (i.e., with eyes and fingers) to see if there's a pinch or other problem in the wiring harness especially with the #6 injector.

The PCM normally grounds the injector to fire in most designs, so I'd be looking for a short that shouldn't be there - but DO check the FSM to make sure that's how it works!

RwP