On Tue, 19 Nov 2013 15:53:35 -0800 (PST), Calvin wrote:

I have to admit that it's some time (ahem!) since it was serviced so
dirt/soot on the photocell would be quite a possibility. It was
installed about 17 years ago (doesn't time fly!) and I'm sensing that
fuel starvation due to the oil pump wearing out is quite a popular fault
on these boilers after a much shorter time than that. That might fit
with the runs-for-a-bit-then-stops nature of the problem.

Could be but I wouldn't like to say that. Our burner (Rielo I think,
there is less than a handful of burner makers) is of a similar
vintage and seems fine.

As yours has not been serviced for "a while" it could just be a worn
jet not atomising the oil well enough for a weak spark due to eroded
electrodes not igniting it reliably and soot on the photocell not
helping.

--
Cheers
Dave.