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 ProblemsIntake Manifold May Crack Leaking Coolant Behind the Alternator
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 throttle position sensor (TPS) may fail. Common symptoms of a defective TPS can be rough idle, hard starting, hesitation on acceleration, poor fuel economy, and stalling.
If you experience difficulty starting the engine when cold, stalling at idle, or hesitations during acceleration, it may be the idle air bypass valve. This valve helps the vehicle idle steady when the accelerator pedal is not pressed.
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