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Discussion Starter #1
1992 5.0L LX Convertible. Cranks but doesn't start. I replaced spark plugs, ignition coil, distributor cap/rotor, fuel pump, and fuel filter. Tested spark successfully. Tested fuel pressure successfully. Sometimes the fuel pump runs continuously with KOEO. Sometimes it doesn't run at all. Bought an OBD1 Code Reader. Test doesn't show any codes. Pulled the EEC-IV computer and saw the capacitors were bad. Replaced those. Still no codes. Still doesn't start. I am at a loss. I have no idea what to try next.
 

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The very first thing when diagnosing an eec issue is to replace the ecu relay.

If the pump runs continuously at times that means the ecu memory is corrupted or is having internal hardware problems. Verify first there is no chip on the J3 port of the ecu. If there is yank it off. If not make sure none of those contacts or shorted out. Otherwise the ecu is the most likely culprit. Verify the check engine light comes on with key on engine off to verify the ecu is powering up and coming on.
 

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Discussion Starter #3
Thanks for the info. I removed the fuel pump relay and ECU relay to look for damage. They look pristine. Just in case they're not clicking, I ordered new ones along with a new ignition switch. Once I have these installed, I'll try to start it again. I also checked fuse linkages connected to the starter solenoid. They look fine. Pretty sure all of my grounds are tight, too. If these new relays and switch don't work, I guess I'm preplacing the ECU.
 

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fuel pump running cont is a sign ECU is not doing its thing.
 
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