There are 2 owner-reported fuel system complaints for the 2003 Mercury Mountaineerin NHTSA's database. These are unverified consumer reports and may not reflect confirmed defects.
TL* THE CONTACT OWNS A 2003 MERCURY MOUNTAINEER. WHILE DRIVING AT VARIOUS SPEEDS, THE VEHICLE SUDDENLY SHUT OFF. THE VEHICLE WAS TAKEN TO AN INDEPENDENT MECHANIC WHO DIAGNOSED THAT THE FUEL PUMP WAS FAULTY. THE FUEL PUMP WAS REPLACED, BUT THE FAILURE CONTINUED. NO FURTHER INFORMATION WAS AVAILABLE. THE MANUFACTURER WAS NOT NOTIFIED OF THE FAILURE. THE FAILURE MILEAGE WAS 113,000.
2003 MERCURY MOUNTAINEER 4.6L-V8: WHEN THE VEHICLE IS NOT UNDER ACCELERATION [STOP SIGN/SIGNAL, EXITING AN EXPRESSWAY TO A SURFACE STREET, COASTING] THE ENGINE WILL NOT HOLD IDLE, THEN STALL. THE STEERING & BRAKES ARE COMPROMISED WHEN THE ENGINE STALLS. TO RESTART THE ENGINE, THE HEADLIGHTS GO DARK FOR A MOMENT...THIS IS A VERY SERIOUS MATTER. DECELERATING FROM AN EXPRESSWAY TO A SURFACE STREET, ON A CURVED EXIT RAMP , AT NIGHT MAKES FOR AN OUT OF CONTROL SITUATION WHERE THE DRIVER CAN NOT SEE BECAUSE OF ENGINE FAILURE! I'VE REPLACED THE THROTTLE POSITION CENSOR [TPS] WITH NO IMPROVEMENT. THE DEALER OFFERS REPLACEMENT OF PARTS $1500, AND NO GUARANTEE OF SOLVING THE PROBLEM. THE VEHICLE IS USELESS TO ME FORE IT IS A HAZARD TO BE ON THE ROAD...FOR ME AND ANYONE ELSE DRIVING NEAR ME. *TR
Complaints are unverified consumer reports submitted to NHTSA. A high complaint count may reflect vehicle popularity, not defect severity. Data sourced from NHTSA public records.
Data synced from NHTSA on Apr 26, 2026