1990 Bronco 5.0 will not run with SPOUT connector plugged in.

[miesk5]

Yo H,
Time to pull the EEC.
EEC IV PCM Removal up to & include 87- 91 COMPENDIUM:
"To remove it first disconnect battery & get use 10 mm socket to unbolt the wiring harness "connector from inside the engine bay. Then pull plastic kick panel from inside cab & remove the retainer clip Remove it by lifting rear slightly & wiggling it out of the "pocket" ... the firewall rubber gasket will have a pretty good grip on the connector so it will take some persuasion to free. "
"You have to unplug it under the hood very low on the fire wall (10 mm socket)."
"..Remove driver's inside kick panel adjacent to pedals. It comes out through cabin." by Seattle FSB;
"Should be one small metal ***** holding it. Just slide it out, but be careful w/ gasket for firewall. mess it up, you can reuse it." by Darth_ted_82

 

[Motech]

Factory Ford trained and 30 year Ford driveability specialist technician here.

Any and every Ford TFI system I've diagnosed that starts or runs better with SPOUT disconnected is always a faulty PIP sensor (Profile Ignition Pickup). This is the stator that lives in the distributor. It generates an analog, AC voltage signal to the TFI module, where it is converted to a digital 5 volt DC signal that is then sent to PCM.

If you measure the voltage at the SPOUT input side with a DVOM, it will average out the signal and give you a 2.5 volt reading under normal running conditions. This is a relatively useless measurement though, as the only way to evaluate that signal is with a lab scope or a quality graphing meter.

Replacing the sensor requires rebuilding the distributor, which requires specialty gear pressing tools that most mechanics do not even have these days. Especially Ford dealership mechanics,

Your best bet is just replace the distributor. That will fix your problem.

 

[miesk5]

Yo
"...noticed that when I unplugged the SPOUT connector to check base timing, and let the engine run at base timing, it never died. Unfortunately, this pointed me back to the PCM as a possible cause of my fault. But, when I plugged the SPOUT connector back together, I could make the engine falter and die by gently twisting the harness. Yes! I was sure I had located the fault, and I was right. Look at the figure with the yellow spark output signal wire that is without a section of insulation.

This section happens to run through a shield ground that provided a convenient ground source for the SPOUT signal. Just the right bump in the road or vibration from the engine would provide a path of lesser resistance for the SPOUT signal, killing the coil trigger..."

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