rich burning

[ROD1969]

1990 chev 1/2 350, i pulled my trailer this summer and the truck seem to be not bad on fuel, the last couple of months it seemed to get harder on fuel and the exhaust seems to be quit raw smelling, has new plugs, wires cap and rotor, any ideas????

[budhayes3]

Hmm, could it be oxygenated gas? Not sure when they switch over. Maybe an injector is sticking open or the fuel press regulator diaphragm is torn. Could also have a bad sensor telling the PCM to richen the mixture....lazy o2, engine coolant temp sensor, map, etc. Would need a scan tool to run a data stream and check the readings.

 

Just a couple of ideas.