Need help on 94 ranger either short or bad alternator or something else

[Mechrick]

Truck is bank-fired, if you didn't unplug them you were ohming out two at once. 7.4 x 2 = 14.8 which is in the ballpark, so I'm betting they are ok, but let me know. Injectors should be white or light gray in color.

 

[dean94]

Injectors are denso f03e-a2b and look like they used to be white

 

[dean94]

Injectors with harness disconnected ohmed at 14.4 to 14.8 with alternator connected and turning over tps voltage never went above 5.11 volts and voltage to battery never went to charging voltage i have videos of truck with belt on misfiring and videos of truck running with belt off files are to big to upload

 

[Mechrick]

Where are you checking tps voltage? Reference voltage is 5v, one pin should be ground and the remaining pin should vary 0-5v with the throttle.

 

[dean94]

Far left wire and ground I'll go make sure I'm in right sport update checked to make sure I was in correct spot and the middle wire varies when I move throttle middle wire didn't go over 4.98 with truck off key on

 

[SenorNoob]

Can you have the meter hooked up the same way and try to connect alternator while running? I'm wondering if there is a spike.

 

[dean94]

Tps voltage stayed this time at 5.03 volts and when I turned it over and engine attempted to run stayed at 5.03 volts

 

[franklin2]

I don't understand why the battery seems so distant in your electrical system. It obviously has enough power to supply the starter. And to run the computer and the ignition system.

But when it comes to absorbing anything the alternator may dish out, the battery is not taking care of it. If the alternator went wild and went full output charging, the battery normally absorbs this. The battery may get to 16v or a little higher, but it takes care of it as long as it can before it starts boiling and has a meltdown. The electronics of the truck can handle 16-18v.

If the alternator had a A/C component in it's output because of a bad diode, again the battery acts like a large tank, absorbing any spikes in the voltage.

Most of the time very weird things in a vehicle can be caused by a bad ground. I have seen melted ecm ground wires because the main large ground was bad. The alternator uses the engine block, and the engine block uses the large ground to connect to the battery. If this goes bad, it will search any wire it can to try to ground itself back to the battery. But usually when this happens you will have melted, smoking smaller ground wires. But you have been all over this thing lately, I would think you would have come across any smoking melted wiring.

This is a tough one.

 

[Mechrick]

The gray/white wire should be the one you are checking for tps voltage. Should be 0-5v and vary with the throttle.

Have you checked codes?

I'm still thinking either something is breaking down over 12v or the PCM is shutting down a circuit that is borderline overcurrent when the voltage exceeds 12v. I've seen both in the field. Check underhood for obvious problems like oil-soaked wiring harnesses, bare wires, etc.

Backfires are usually ignition-related. Scan for codes, inspect the crank sensor/harness, if all looks good start substituting parts. Might be a good idea to source used ignition module, coil pack and throw a new (cheap) crank sensor at it.