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Test the electrical circuit for the fuel pump , lab scope an amp test meter ! Find the fuel pump relay ,pull it out ! Look on bottom of the relay . Should see four sets of numbers , 30,87 an 85,86 . take a DVOM - set on DC amp's . put one lead at 30 an other 87 . This is power to fuel pump . Should see 4 - 6 amps current draw ! Videos on youtube showing this !
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.
Sometimes a crankshaft sensor does not send the signal to fire either the spark or the fuel injectors. If the fuel pump relay is not getting power, the inertia sensor will not have power either. The inertia reset is just magnetic and does not depend on having power to reset.
You can check for current at the Inertia sensor and at the fuel pump relay. You can also have fuel pressure at the test port without the injectors working, which is the easiest test of all,
You need the sequential firing pulse for the injectors. Have you checked the EEC Relay?
Move over there's a fat guy here to help you now you must go to fordowners.com register for free then search for your owners manual you can download it for free then go to roadside emergencies and look for your fuse box diagram there will be the fuse location for the fuel injection and there's a relay for them to I believe
Listen for the fuel pump to turn on with the key ON. Do you hear it buzz on for a couple of seconds, and then shut off? If you do, the pump is working. If you don't hear it, the pump is bad or the wiring to the pump is not working. Check the relay. Usually, on a four cylinder with multi-port injection, injectors 1 and 3 fire simultaneously, and then injectors 2 and 4 will fire at same time (because their ground wires are spliced together before entering the computer. When the computer internally grounds the wire, the injectors will pulse). Are you certain that all four are pulsing at same time? If so, that may be the Mazda way. But I think you are right to believe it is a fuel problem. Test the pump as stated above, key on (not start) and listen for pump to turn on. Good luck.
Check all the fuses,and check the fuel pump relay,if this checks out o k,See if there is fuel pressure at the fuel injectors,if there is,then the injectors are not pulsing.The cause of this is the pick up coil in the distributor,but replace the distributor as a whole,this has all the components in the distributor,That control the fire,and the pulse to the injectors,A used one might be more economical sound money wise.
check cold start injector relay and injector. are u sure that fuel pump is good? can u hear it come on when key is turn to on ? it should come on for about a second if yes check for fuel from injectors , pull one injector put from head point into glass jar remove rubber boot from air flow sensor assembly, pull fuel pump relay and install jumper so fuel pump contiously runs then using a magnet pull up on air flow sensor fuel should be coming out of injector in a cone shape.
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