modena 102?

First of all make sure your pressure is between 1 -1.5 bar.
I suspect that your timer is faulty. By linking a wire across terminals 3 and 5 of the timer you can prove or disprove this.
It is generally speaking not a good idea to DIY on gas appliances. I recommend you employ the services of a Corgi registered repair engineer.
If you need any more help may I refer you to DIYnot.com where there are more experts and the site has evolved to be more suitable to helping people with boiler problems.

Slugbabydotcom
November 2007