Burnt valves will cause power loss. Another symptom will be the engine will run hotter than normal and use more antifreeze.
Engine cylinder head valves admit the air/fuel mixture and release the burnt gases.
The fuse has burnt out.
a burnt rubber ball in the cardorater
timing off,base timing not set,dist. not set in right position, timing belt about to break, low fuel pressure,burnt valves,leaking head gasket.need more symptoms.
This could be any number of things... a slipping belt, burnt valves, old bearings. Try plugging some of the car symptoms into this search engine... it's handy: http://findzer.com/searchengines/000017.html
blue smoke can be caused by sticking valves or burnt rings
Exhaust valves open at the appropriate time to allow the burnt gasses to escape.
You can have a compression test done on the engine to determine the condition of the rings and valves.
Burnt valves need to be lubricated where the valves move up and down there is alot of friction and whats to keep it lubed is oil if you dont keep that up that is where the blue smoke coming out the tail pipe.
The bulbs are burnt out.
The valves in a car engine are opened and closed by a cam shaft driven by the engine crankshaft. they allow the flow of gases and fuel into the engine and the burnt gases out of the engine into the exhaust system.