the odd time you hear the clicking and it lights is when its got through its sequence, if you only get pump the remainder of the time then you need to work from there.
generally, pump runs, fan runs, fan pressure closes circuit on air pressure switch (proving fan is running) then ignition and gas so see where it gets to, to find your fault.
so does fan spin?
if it does is it spinning freely?
are aps tubes clear and not brittle/broken?
is venturi in fan clear (where tube connects)?
iain
June 2008