1990 ford festiva no power to fuel pump. replaced relays , fuel pump, checked safety shutoff. nothing .. ran hot wire to fuel pump and pump worked but car still not trying to start. got spark. now what

did you test your inertia switch and its circuit

Only Ford products have a fuel switch called an inertia switch.
GM products use a fuel pump relay and the oil pressure switch to provide power to the pump.

Apparently the relay is not being turned on. I believe that signal would come from the engine computer. Does your check engine light come on when you turn the key to on? If it does, the computer is powered up-if no check engine light, either the bulb has burnt out or the computer has no power-check for a bad fuse.
Put your finger on the fuel pump relay and have someone turn the key to on. Do you feel the relay tick? If you do, check if the relay has one hot wire with key off-use a voltmeter or a testlight. If you do have a hot wire at relay., check fuel pump wiring from relay to the pump. Pull off the connector at the pump and replug it back in.
If you can't find a powered wire at the relay with key off, maybe it is only hot when key is on, so turn key on and check relay again for that power wire going to the relay, one wire should have constant power there. If not, there is a wiring problem between the battery and the relay. If the relay has power to it, but you felt no pulse when turning the key to on, likely the relay is not getting a signal to turn on. A shop would need to investigate that.
Well, good luck, hope you find the problem.

No, Chrysler does not use an inertia fuel shutoff switch like ford. There is nothing resettable or anything like that with the fuel system. You can disable it by pulling the ASD relay or fuel pump relay/fuse. If you have a problem, you can check your relays and swap them around to see if that solves your issue.

Hope this helps!

in engine bay near battery there is a power relay that is probably the issue.

defective new pump
Mike

check near the battery, the ground wire may have come loose or is not making good contact

something is killing the relays poss fuel pump drawing to much amperage check pump with amp probe is pump noisey?

If you have the ignition in the on position remeber the fuel pump only runs for a couple of seconds unless the car is activley being started

I have found the relay at my local auto parts recycling center, after many hours of troubleshooting, I also found the PCM to be faulty. A replacement computer is on order. This model has been modified by prior owner removing the inertia safety switch. A replacement is also being sought. A similar problem occurs when the ECT (engine coolant temperature) sensor is destroyed.
Whatever you do, DO NOT REMOVE THE INERTIA SAFETY SWITCH. This does protect the fuel pump and related circuit. Also linked to the fuel pump circuit is the main relay, and the injectors.
If you find the thermo fan starting within seconds od rotating the engine, the problem is the main relay earth, PCM (needs replacement) and/or the fufel pump relay. This is known as LIMPO HOME MODE.