power problem

Asked by Sep 27, 2016 at 08:07 AM about the 1989 Ford F-150 S Standard Cab SB

Question type: Maintenance & Repair

I have a 300 straight 6  it fires up and runs  but
there is power loss when going up hills and while
driving  I replaced the fuel pumps  the filters and
most of the sensors  idk what else could be wrong

11 Answers


have the plugs been replaced recently? Check the resistance of the plug wires. It's a process of elimination. If your spark is ok, then check fuel then air. Try cleaning the throttle body and check the IAC.

The plugs are less then 2 months old I pulled throttle body off cleaned and reinstalled fuel has new pumps and filters. New air filter What's the iac?


Didn't notice the year of your vehicle. IAC stands for Idle Air Control Valve. It's a circular metal electrical device attached on the top of the intake manifold just past the throttle body. Visit an auto parts store and plug in the year, make and model of your vehicle. It will show a picture of the device.


When going up hill or under load is there a feeling of hesitation or slight perception of jerking/missing? I've been driving Fords since 1970. I've learned they are rather finicky when they come to spark plug wires. I suggest you have a place like autozone run an OBD code check. It may have thrown an internal code which will lead you in the proper direction. Stop purchasing parts at this point until a diagnosis is performed (electronic).

Yes sometimes even when not on a hill or lose it acts like it's not getting enough fuel. Then a slight kick and gets whst power it has back

After 3 attempts to get code readers to work on my truck I did it the old way that's y I replaced all that I did. Still gota put the new 02 sensor on

Could the bad 02 sensor cause this problem


You may have to go to a shop that has a live data collection computer which will plug into the PCM code reader. The mechanic can hook up the reader and go for a ride, recording the data which will record all perimeters of varying driving conditions and speeds. The electronic readings can then be played back without the vehicle being driven to determine the error/malfunction. The analysis shouldn't cost more than one hour shop time labor to determine the cause.


I could, depending on the vehicle, your vehicle is approaching age 30 and characteristics could vary. Here are some symptoms of a bad O2. First, the idiot light will illuminate on newer vehicles. If the O2 sensor is bad the PCM may try to adjust things like timing and air/fuel mixture to correct for the problem. You may notice a difference is gas mileage as more fuel may be supplied to correct the condition. A rough idle or misfire condition could be present. I am not familiar with your vehicle in particular so check and see how many sensors you have. You could have as many as 4. An internet check for your particular engine may lead you to info about which sensor(s) is most likely to go bad. Many parts store have a no return conditions on these type of parts.

Replaced o2 now to drive it for the week to see if any changes

After 2 days of driving to work I have more power back with the new o2 just not 100%

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