No injector pulse 4 cyl 93 f250 460
if you have a $5 test light, you could find the problem. just know that all eight injectors have a constant voltage applied to them anytime the key is in run or start. and also that 4 of the injectors share a common ground, they have their ground wires spliced together before the ground wire enters the pcm to be internally grounded. and the other four injectors are the same- their ground wires splice together. so your four that don't pulse have lost either the power to them, or the common ground wire for the 4 may have broken. or lost connection.
it is easier to check the power side first, so clip a test light lead to the negative battery post or cable, turn the key to on,and probe each injector connector. one of the terminals at all eight injectors will be the power wire, and it should light up the test light. if all eight injectors have power to them, you know it must be a ground side problem. if you find that 4 injectors have no power to them, look for a broken splice in the power wire to all injectors. back in those days, injectors were "bank fired". one side or bank of the engine all had the injector grounds spliced together, so all injectors on one bank fired (pulsed) simultaneously, and then the other bank was fired or pulsed. that was good until sequential injection matched the pulse to the cylinder ready to fire, more precise, and in the modern systems each injector ground has a separate ground inside the pcm. no more splicing of the ground wires, and having bank fired engines.
when the pcm grounds the circuit, the injector coil is energized and the injector opens to spray fuel out. so the injector has constant voltage to it. only when the circuit is grounded is that power applied across the injector.
Jan 22, 2015 |
Cars & Trucks