Bad gas mileage and sluggish on load

MICHAELPROWELL2

MEMBER
1994 FORD RANGER
4.0L
V6
2WD
AUTOMATIC
167,000 MILES

The truck will not start up first thing in the morning without spraying starting fluid. Also runs very sluggish when put under load. Gets bad gas mileage and black soot and smoke out of exhaust. What is my problem? I have replaced fuel pump fuel filter TPS MAF sensor, fuel pressure regulator, injectors spark plugs, and wires, also fuel filler hose.

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,772 POSTS

Hi and thanks for using 2CarPros.com.

If you are getting black smoke from the exhaust, the engine is running too rich. (Too much fuel being injected into the engine) If that is the case, make sure the air filter and inlet tube is not plugged. Also, there is an engine coolant temperature sensor (ECT) for the computer and not the gauge in the vehicle. It provides an input to the Powertrain Control Module (PCM). The PCM uses engine coolant temperature data to adjust the fuel injection base pulse width, EGR flow, and ignition timing. If, for example, the ECT tells the PCM that the coolant temperature is -50 degrees F, the computer will run the fuel air mixture extremely rich so the engine can run in extreme temps. If the outside temperature is much warmer, the engine will run richer than it needs to be.

Here is what I suggest, check to see if there are any trouble codes stored in the system. Here is a link that shows how to check for codes on your vehicle.

https://www.2carpros.com/articles/ford-lincoln-mercury-obd1-1995-and-earlier-diagnostic-trouble-code-definition-and-retrieval

I suggested checking for codes to make sure there is not another issue. The tough thing is this. Even if the ECT sensor is sending a false temperature signal to the PCM, the PCM does not know it is wrong and will not show a code.

If you decide to replace the sensor, here are the directions.

COOLANT TEMPERATURE SENSOR
REMOVAL

NOTE: The Engine Coolant Temperature (ECT) sensor is located in the lower intake manifold near the water outlet connection.

1. Disconnect negative battery cable.

2. Partially drain cooling system.

3. Disconnect ECT sensor electrical connector.

4. Remove ECT sensor from lower intake manifold.

INSTALLATION

1. To install, reverse removal procedures.

2. Tighten the ECT sensor to 8-13 Nm (6-8 ft lb).

3. Refill cooling system.

NOTE: When the battery has been disconnected and reconnected, some abnormal drive symptoms may occur while the power-train control module relearns its adaptive strategy. The vehicle may need to be driven 10 miles or more to relearn the adaptive strategy.

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Let me know what you find or if you have other questions.

Take care,
Joe