im having a mysterious problem with my truck. i have a 93 3.9ltr,the truck would run for 5 to 30 min,then all of a sudden it would just quit.would give know sign that bit was going to quit.there have been a load of parts changed on this truck,from fuel pump,fuel pump relay,auto shut down relay,crank sensor.i put a thread on here earlier and people have said to look for corrosion
neer the battery,i have stripped all the wrapping around the wires and found no corrosion,i checked for codes and got code 12 and 55. dont know what else to look for. need help thanks joe

 

If it were a sensor or a relay, chances are it would pop up in the codes. Could be a fuel pressure regulator, fuel filter, could need a good tune-up, vacuum leak, faulty plugs, incorrectly gapped plugs, emissions system parts faulty (such as the catalytic converter), incorrect idle speed/timing, etc.