5.8L-Fuel Pump Runs Continuosly

[RustyB]

I have a 94 Bronco with a 5.8L engine and 300K miles. This morning, the truck cut off suddenly, and now cranks but will not start. When the key is turned to the on position, the fuel pump runs continuosly instead of turning off after a second or two. Also noticed a strong "burning plastic" smell in the cab, but cannot smell it under the hood. I recently replaced the fuel pump and alternator (3 months ago, daily use since), and have had no problems until now. I was thinking perhaps a wire is grounded out in the fuel circuit. Any other ideas? Thanks!

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[Hayapower]

Might verify a spark present too, visually check under the dash just in case, and give the PCM a good sniff...

[RustyB]

I ran all the wires under the dash and steering column, cant find any evidence of anything burned. Checked the fuel pressure on the rail and its at 40 psi. Replaced the fuel pressure regulator as well, still have the same problem. Pulled spark plug, and engine ids getting spark. When I remove the battery cable and reattach, the engine will start and run foro about 10 seconds, then the problem starts all over. Where is the PCM, and is that the same thing referred to as the EEC-IV in the haynes manual?

Anything else I should check? Thanks again for the help!

[RustyB]

Hayapower, good call on sniffing the PCM. I pulled it out and thats where the smell was coming from. I pulled the cover and there was a big burned spot in the center of the board, and part of the circuit board was melted. Got a new one on the way. Thanks for the help!!