What causes unburned fuel in exhaust?

Unburned Fuel Entering the Exhaust System. This can over-heat the converter far beyond its normal operating limit. Possible causes are an improper fuel mixture, incorrect timing, bad spark plugs, a malfunctioning oxygen sensor, sticking float, defective fuel injector or a faulty check valve.

Can a bad distributor cause loss of power?

Bad spark plugs, fouled-up plug wires or a cracked distributor cap can cause spark loss, while compression loss — in which too much of the air-fuel mixture flees a cylinder before going bang — commonly arises from a leaky exhaust valve or a blown head gasket [sources: B&B; O’Reilly].

What are the signs of a bad distributor?

Usually a faulty distributor rotor and cap will produce a few symptoms that alert the driver that service may be required.Engine misfires. Engine misfires can occur for a number of reasons. Car doesn’t start. Check Engine Light comes on. Excessive or unusual engine noises.

What are the signs of a bad distributor cap?

Bad Distributor Cap SymptomsYelling Noises. Squealing noise from the car is the first sign of a bad distributor cap. Difficulty in Starting. Some of the bad distributor cap symptoms. Shaking. You might have experienced extreme shaking or vibration when starting or shifting the gears. Stalling and Backfire. Difficulty Turning Over.