Many thanks to all who replied with helpful suggestions. I worked through
all the suggestions and by the time I did that the original post had lapsed.
The problem has turned out in the end to be that old bugbear - dirt in the
fuel. I have now fitted an inline auto fuel filter bought at the local motor
factors for about £2. It has more than enough capacity and renewing it
every year will be easy and cheap. The problem in sourcing the stopping was
that when I ran the thing on a bench, when it worked without hiccup, it was
using a different fuel system. Lesson One is look at the obvious first! - D


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.493 / Virus Database: 292 - Release Date: 25/06/2003