Injectors not firing. 1994 3.0 - Ranger-Forums - The Ultimate Ford Ranger Resource

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Old 06-20-2015
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Join Date: Jun 2015
Location: my house, sc
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Injectors not firing. 1994 3.0

Hey everyone. First post. I'm having problems with a 1994 Ranger 3.0 I bought recently. The truck sat for a few years before I bought it. I replaced the fuel pump, filter, plugs and wires, and starter solenoid and the truck was running great. After a week or so it got harder and harder to start and ran rougher and rougher until it wouldn't start at all.

I have fuel to the rails, and the plugs are firing. It will start with starting fluid. It looks as if the injectors aren't firing. There were two stored codes when I checked them. One for the MAF and one for the pick up coil. I don't remember the actual codes off of the top of my head and I can't find where I wrote them down.

If I'm understanding it correctly, the pickup coil is on the distributor and doubles as the camshaft sensor and the crankshaft sensor.

Is this more likely than a bad computer?

Is there anything else that would control the injectors? Does the ICM have anything to do with the injectors?
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Old 06-20-2015
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1994 3.0l still had distributor and TFI spark system, yes, TFI module(ICM) sends a PIP(pulse) to computer to time fuel injectors with spark.

TFI doesn't need computer to run spark, but computer needs TFI pulse to run injectors.

Good read here on TFI system and checks you can do: Ford EEC-IV/TFI-IV Electronic Engine Control Troubleshooting

All fuel injection computers have a way for the driver to shut off fuel injectors.
This is there to "Clear a Flooded Engine"
The TPS(throttle position sensor) sends computer 1 volt when key is on and your foot is off the gas pedal, if you press the gas pedal to the floor the TPS sends computer 4.5 volts or higher.
If TPS sends computer 4.5volts and RPMs are 0(key on/engine off) the computer will turn off fuel injectors until TPS voltage is below 4.5v.
This allows the driver to crank the engine and clear it out if flooded.

BUT........if TPS(or it's wires) should short out and send 4.5volts all the fuel injectors, so no start.
Unplug TPS and see if engine starts.

top wire on TPS should read 5volts
center wire, below 1v throttle closed, above 4.5v throttle wide open
lower wire is ground
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Old 06-20-2015
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Join Date: Jun 2015
Location: my house, sc
Posts: 2
Unplugging the tps doesn't change anything. I don't have a lot of time now, but I'll read the link you posted today or tomorrow. Thanks.
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