Greetings,

I would value opinions on this little problem.

The Vehicle. This is an American import for those who don't know and is a V6 (Auto). Fuel injected and looks similar to the Ford V6 engine as seen in the old Granadas etc. Also runs on LPG.

Background. Owner was driving at approx. 50mph over bumpy ground and cut out. Driver switched over to petrol and still non-start.

My Checks. No fault codes and little useful live data shown. HT present using special Crypton gizmo and fuel present as shown as 5000+ ppm HC. No response from a "sniff". Vehicle cranks well but not firing. Compressions on all cylinders show on average 150 PSI. Timing checked and OK. Now heres the thing. I wanted to find out what the vacuum was on cranking which was 15" hg on WOT with throttle intake covered. This test resulted in the vehicle firing for a few seconds and will do so now when trying to start it normally with everything intact. So this vacuum test has now prompted the engine to fire and run for a few seconds but will not rev.

My Thoughts. I think the cat may be blocked but want to elicit opinions before going down this road. The vehicle was driving down a bumpy road and when it cut out it prompted the owners wife to think something has "dropped off".

Many thanks in advance for your collective wisdom.

Regards

Pete M