Ok been doing some further investigations,
- decided not to change any of the electronics until I was sure of any cause.
- On the basis that once it starts it ran and drove OK albeit with some idle issues I decided to look for vac leaks so stripped the inlets off and all breathers to do a detail inspection. The car is 30 years old but only covered 52k miles but still all the rubber bits are getting on. Changed the stepped pipe by the oil filter , both large breathers running across the back of the engine various other rubber bits , breather gasket at the back of the engine as I was in there anyway. Connection to the brake vac circuit looked suspect so renewed that. The car now runs much better and no erratic idle and now starts from cold without problems.
- The hot start issue remains though, if you leave the vehicle to stand, the engine will crank over merrily but it is reluctant to fire, eventually does fire but then cuts out , if you crank again it starts and then cuts out .... on the third or fourth attempt to start it, it then runs rough and then settles down and is fine.
- So my conclusion is its fuel pressure on the basis it starts cold ok so no fuel vaporisation issues but when hot the accumulator should retain the fuel under pressure and avoiding fuel vaporisation. So think either pressure regulator or pump is suspect although once running the car is fine so suspect pressure regulation is the more likely cause.
Anyone have any views on this?