In article .com
babybanks wrote:
Hi all, I have seen a few posts with lots of information about oil
fired central heating systems so am hoping someone could help me out. I
have the sneakiest feeling my ex has sabotaged my oil fired central
heating by putting something like sugar in the tank. How would I go
about finding out if he has? Its still trying to kick in but stops
again after about 3 seconds. (i was turning down the main thermostat
the turning it up again) other than that it was fine up until this
morning....

Are you sure there isn't water in the tank? Seems more likely to me.