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1991 Ford F-150 Problems

RepairPal has identified the most common problems with the 1991 Ford F-150 based on complaints from actual vehicle owners. We'll tell you what the problem is and what it'll take to fix it.

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9
Known Problems

The Ford F-150 has known issues with the V8 engine ejecting spark plugs. This will make a tapping or knocking noise, plus the engine will begin to misfire at all speeds. The check engine light will also illuminate.

The threads on the cylinder head are too short and soft, allowing pressure from combustion to overwhelm and destroy the threads. 

When the spark plug ejects, the cylinder head becomes damaged, necessitating repair of the spark plug port threads, or replacement of the cylinder head and cylinder head gasket. 

Ford has recommended a method of repair for the cylinder head that prevents the spark plug from ejecting under future use. Replacement of all spark plugs is not necessary, but an updated spark plug design can help prevent this from happening in the future. 

There is a technical service bulletin for the V8 engine.

The engine oil pan gasket can develop a leak. Leaking oil may accumulate on the exhaust system resulting in a burning smell. Replacing the gasket should correct this leak.

The Ford F-150, with the optional 5.0L/302ci V8, may develop misfires, rough running, and loss of power, accompanied by the check engine light illuminating.

Ignition wires can rest on the exhaust manifolds if they are not properly secured. The hot manifolds will melt the insulation on the wires, damaging the wires and causing the mentioned condition. 

Replacement of the ignition wires, and securing them away from the exhaust manifold is necessary to remedy the rough running conditions. 

A ticking noise may develop from the engine due to a warped exhaust manifold. Damaged exhaust manifolds will require replacement to correct this issue.

Catalytic converters can go bad and potentially plug the exhaust, hurting engine efficiency and performance.

The battery light may illuminate on the instrument panel because the alternator wire harness connector is damaged. A new connector kit is available and should be installed to correct this concern.

The front brakes may stick, bind, or grab. This can happen when the front brake caliper pins become corroded. Cleaning or replacing the caliper pins will be necessary to correct this problem.

The gears for the timing chain can strip, causing the engine to crank but not start.

Failure to change the power steering fluid can cause the fluid to become gray with metal particles. The contaminated fluid can damage the power steering pump resulting in a growling noise when the wheel is turned; the damaged pump will require replacement to eliminate the noise.. Life of the power steering gearbox and pump will be shortened if the fluid is not serviced regularly.