1991 Mercury Grand Marquis Repair and Maintenance
A guide to problems, costs, maintenance and repair for your 1991 Mercury Grand Marquis
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1991 Mercury Grand Marquis ProblemsMalfunctioning Headlights
The car had 64600 miles on it and the headlights started going out while driving, which can be very dangerous. The problem is in the Light Control Module which is an expensive part (around $500 to $600 + labor).
The composite (plastic) intake manifold may crack near the thermostat housing and cause a coolant leak. Ford released an updated manifold that was reinforced to prevent a recurrence. No recall was issued for this problem but Ford did extend the warranty to seven years on some models from the date of purchase.
The EGR valve position (EVP) sensor can fail on this vehicle. The EVP sensor measures the EGR valve position and transmits the date to the engine control computer. If it fails, drivability and fuel economy can suffer, the Check Engine Light will commonly illuminate.
1991 Mercury Grand Marquis Questionswhy is my oil light coming on when i come to a stop (1 answer)
The oil light comes on ehen I stop but comes off as the car starts moving