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I'm getting the following codes on my 1994 F Super Duty. I've changed the EGR valve, and coil, the truck runs but I would like to get the check engine light to quit coming on. Can anyone please help me get in the right direction:
311 Thermactor air system inoperative
332 Insuffienct EGR flow detected
542 Fuel Pump Secondary Curcuit Failure
556 fuel pump relay primary circuit fault
558 electrical circuit of EVR
When I bought the truck the cat was removed. I have replaced all of the ignition components. I have noticed that when the ignition is turned on but motor not started the fuel pumps run constantly, both tanks do this. Also when I run down the highway my check engine light will come on but only when I get ready to shift into fourth gear. I can stay in third gear and it never comes on but the point I go to fourth it comes on.
Not an expert but the fuel pumps running all the time is not good. Try unplugging the PCM (computer) and switch the key to on. If the fuel pumps do not run I would think the computer may be bad.
However maybe some of the experts will give an opinion soon.
It looks like someone removed some items they did not like being there and rewired the fuel circuit to there liking.
But do as Lazy K said and you might be lucky and it is just a bad computer.