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Discussion Starter · #1 ·
I have a 3.9 in my 94 dakota. Within the last 2 months, it takes long crank times to get it to fire up and run after sitting overnight and sometimes even after sitting all day. Once it starts up, it idles and runs smooth. It also re-starts right away after that first start as well as if the engine is warm. Its getting worse (longer time cranking until it fires up). Also during the process it will first sputter (not fire on all six) and sometimes backfire before it fires up smoothly on all six. I also can smell gas after the cranking and when it fires up. I can also hear the fuel pump cycling with the multiple "key ON" routine.

I've:

  • Changed the fuel pressure regulator on top of the fuel pump,
  • Changed the ignition coil,
  • Changed the Engine Coolant Temp Sensor (2 prong unit by the AC comp),
  • Cleaned the distributor cap and rotor.
I also checked for spark directly on the high tension post of both the original and new ignition coil when the problem arises and NO spark exists at first which correlates to the long crank times.


Battery is under a year old. Also I live in the tropics so its humid and "cold start in the morning" is 70 degrees for me. Finally I noticed 2 days ago when we had some wet weather that it had a longer crank time then the days previous to that.


I'd appreciate any thoughts or suggestions.
Thanks,
 

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I don't see "ignition wires" up there; that's more common to cause hard start when damp.

Also, try this:

1) Disconnect the negative battery cable.

2) Remove the ECU connector.

3) Reinstall the ECU connector.

4) Repeat 2.

5) Repeat 3.

6) Repeat 2.

7) Repeat 3.

8) Reconnect the negative battery cable.

After that, see if it's improved any.

Might just be age and oxidation in the contacts in the ECU; this will polish them and get it back running. If this does it, repeat 1, 2, load the connector up with "bulb grease", and then repeat 7 and 8.

RwP
 

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Discussion Starter · #3 ·
RalphP:
Thanks for the insight. I didn't touch the plug wires or plugs yet after I did the spark test on coil's output post and it wasn't sparking (even with the new coil as noted before). I figured the problem is upstream of the coil.

I'll try the PCM connector cleanup and if it doesn't yield results, I'll put in new wires, cap, rotor and plugs.

Also, I did check the distributor mag pickup yesterday and it physically looks good..I wiped up the rotating steel ring for the pickup and reinstalled it.

As a point of reference, I did change the PCM a few years ago when the factory original went bad. In that process I did also change the Crank sensor. Other than that the engine systems are original.
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dakotahall

on my 3.9 1988, pcv, same hard cold start, yes the pcv was clogged, couldn`t believe it, about three seconds cranking and start, also changed air filter about week later and starts better, first hit of key. so happy now
 
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