Yo Polarbear72,
Welcome!
Some no code usual suspects by Ford;
Electrical connectors; inspect at coil, distributor, Ignition Control Module, etc. especially those with broken locking tabs, or unwrapped harnesses by a previous owner.
Check fusible links at starter relay.
Did you get opp to Test Fuel pressure before it cut??
Accessories that fail to operate with the key in RUN, or that remain on when the key is turned off, may be the result of a misadjusted ignition switch rather than a malfunctioning ignition switch.*
Does ignition key feel loose in key cylinder? Test the mechanical operation by rotating the Key through all positions of the ignition switch. The movement should feel smooth with no sticking or binding. *The key should return from the START position back to the ON position without assistance* (spring return). If sticking or binding is encountered, check for the following:
burrs on the ignition switch lock cylinder
binding ignition switch lock cylinder
shroud rubbing against ignition switch lock cylinder
burrs or foreign material around the rack-and-pinion actuator in the housing of the ignition switch lock cylinder
insufficient **** on actuator
binding ignition switch
Ensure switch is securely mounted.
Ignition Switch Pin-Out Diagram & Continuity Testing (Logic Tables) in 87-91
@
https://www.broncozone.com/threads/87-91-ignition-switch-info-troubleshooting-guide.14120/ by Broncobill78
Air filter, is it relatively clean?
Air inlet atop radiator support to filter box and to throttle body; look for obstruction; damaged tubing
Fuel quality; Oxidized fuel often turns darker over time and may even smell sour. You can check stored gasoline by pouring some into a clear glass container and comparing it side-by-side with known fresh gasoline. If your old sample looks noticeably darker than the fresh gas, you have strong evidence the gas has gone bad.
"Check Battery Voltage. With the engine running at 2000 rpm, check the alternator output voltage. The voltage should be between 13.0 and 15.0 volts."
Source: by Ford
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EEC IV PCM Removal up to & include 87- 91 COMPENDIUM "...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. Don't mess it up, you can reuse it." by Darth_ted_82 H "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)."
See EEC IV Capacitor Replacement in a 90 by seedpress @
https://www.broncozone.com/threads/fuel-delivery-problem.20788/
Here are some PCM KILLER perpetrators and other causes:
Old leaky capacitors, see seedpress's link above
Smell around the PCM. If it smells like dead fish, it's bad.
Bad Intel 8061 chip or bad Intel 8361 memory chip
Bad resistors or Internal Voltage Regulator, see
http://www.fuelinjectedford.com/images/eec085.gif by Ryan M
Burned PCM printed circuit board circuits (brown burn marks).
Water damage from cowl leaks, ESPECIALLY if you you have wet carpet or mat near driver kick panel; or on PCM Connector due to a bad hood seal near cowl panel, viewable with hood up.
The alternator could be generating an AC voltage spike due to bad diode(s) or supply Voltage Overloads.
I recommend bench-testing the alternator for voltage output and AC voltage ripple.
Thermal stress due to excessive heat and excessive vibration that causes sensitive parts to fail.
Bronco was jump started on reverse polarity.
Overheated PCM.
Corrosion or damage due to moisture is one of the main reasons for failure. Corrosion can enter through the wiring harness and moisture can enter by a failure in the seals in the PCM itself. This happens over a period of time (5 to 10 years) due to exposure to the elements.
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