1. Identify the Cause:
The sticking could be due to several factors:
* Mechanical Linkage: The most common cause is a problem with the mechanical linkage connecting the pedal to the throttle body. This could involve:
* Rust or corrosion: Years of exposure to elements can cause parts to seize.
* Bent or damaged linkage: A collision or off-roading incident might have bent the linkage rod.
* Worn bushings or pivot points: These components wear over time, leading to friction and sticking.
* Dirt, debris, or gummed-up grease: Accumulated grime can interfere with smooth movement.
* Cable (if equipped): Some models might use a cable instead of a linkage. A frayed, kinked, or binding cable can cause sticking.
* Return Spring: A broken or weak return spring will prevent the pedal from returning to its idle position.
* Throttle Body: Less likely, but a sticky throttle plate inside the throttle body can contribute to the feeling of a sticking pedal.
2. Troubleshooting and Repair:
A. Visual Inspection:
* Start with the pedal: Look closely at the accelerator pedal itself. Is there anything obstructing its movement? Is it bent or damaged?
* Examine the linkage: Follow the linkage from the pedal to the throttle body. Look for signs of rust, bending, damage, or binding at any pivot points or bushings.
* Check the return spring: Make sure the return spring is intact and strong enough to return the pedal to its resting position.
* Inspect the throttle body (if accessible): See if the throttle plate moves freely. A buildup of carbon can cause sticking. (This requires more mechanical knowledge and tools.)
B. Cleaning and Lubrication:
* Clean the linkage: Use a wire brush, degreaser, and penetrating lubricant (like PB Blaster) to clean all moving parts of the linkage. Pay close attention to pivot points and bushings. After cleaning, lubricate the moving parts with a high-quality lubricant suitable for moving metal parts (not WD-40).
* Clean the throttle body (if you're comfortable): If you're experienced with automotive repair, you can clean the throttle body using throttle body cleaner. Consult a repair manual for proper procedure.
C. Repair or Replacement:
* Bent linkage: If the linkage is bent, you might be able to carefully straighten it. If it's severely damaged, it'll need replacement.
* Worn bushings: Replace worn bushings.
* Broken return spring: Replace the return spring.
* Damaged cable: If you have a cable-operated system, and the cable is frayed or damaged, it must be replaced.
* Throttle body: If the throttle body is the culprit, replacement is usually necessary.
3. Safety Precautions:
* Disconnect the battery's negative terminal before working on any part of the throttle system. This prevents accidental short circuits.
* Work in a well-ventilated area when using degreaser and other chemicals.
* Consult a repair manual: A factory service manual for your specific 1990 Jeep Wrangler will provide detailed diagrams and instructions.
* Seek professional help: If you're not comfortable working on the throttle system yourself, take your Jeep to a qualified mechanic. A sticking accelerator pedal is a critical safety hazard.
Important Note: Improperly repairing the accelerator linkage can lead to dangerous consequences. If you are not mechanically inclined or unsure about any step, it's crucial to seek professional assistance. Driving with a sticking accelerator is extremely dangerous.
