When methane (#CH_4#) burns in the presence of insufficient oxygen (#O_2#), do the products of the reaction include carbon monoxide(#CO#)?
It can; mind you methane burns pretty cleanly.
Methane is the smallest hydrocarbon, and given sufficient oxygen will combust completely:
Longer chain hydrocarbons, especially diesel fuel, can combust incompletely to give carbon monoxide and particulate carbon:
This is one reason why trucks, which invariably have Diesel engines, tend to have sooty exhausts.
Even in the internal combustion engine, some of the petrol is combusted to give carbon monoxide and soot.