As said, a bit of a leak (hiss when you bend pipes etc) on the 4mm pipe between Matrix and pressure sensor is unlikely to be enough to cause a low pressure reading at the sensor. But you'll want to eventually fix this problem anyway and it would be a good idea to fix it now so you can at least rule this out.

Whilst on the subject of the errors page - The software may show an errors page but we don't yet know if your ECU/firmware are new enough to support error reporting. But it's worth checking to see if any faults register for gas vapour temp sensor... If the ECU picks up on such error it will switch back to petrol anyway.

Recap...

You have ruled out some potential causes such as blocked liquid filter and solenoid. It is very unlikely that the tank pickup pipe has come off, far more likely that there's a problem at the front end such as faulty reducer. The leak(s) as you described them seem to be inconsequential.

1. Will the engine still idle on gas? If so: 2. Does it idle smoothly and on all 8 cylinders? 3. What are gas pressure and vacuum readings when idling on gas? 4. When idling on gas, watch the screen to monitor gas pressure and vacuum readings and very slowly and gently increase rpm (no sudden movement of accelerator).... What happens to those readings?
   ,
   The answer to 1 confirms the most fundamental aspect... whether you're getting gas through to injectors. The answer to this seems to be yes.
   2 Gives us insight into whether any of your Matrix injectors are sticking open... If you get an injector sticking open it will cause a misfire on the affected cylinder, and depending on what size nozzles are on the injectors may be the cause of low gas pressure. I don't think we've had any insight on this yet.
   3 tells us if your AEB025 combined gas and vacuum pressure sensor (2 sensors, 2 figures on screen) seem to be plumbed in properly and working OK. I'm not sure if there's been mention of vacuum readings yet... A lot of Zavoli installers run separate vacuum pipes for reducer vacuum reference and pressure sensor reference. If only one of reducer or pressure sensor is plumbed to vacuum you'll get fluctuating pressure readings if you blip the throttle.
   4 builds on 3 and gives a bit more insight into reducer performance. If you increase throttle position very slowly to get to fast idle of around 1500rpm the manifold pressure won't rise much above what it is for idle at any time while the rpm is increasing, and then at fast idle manifold pressure will be lower than it was at idle, while the amount of gas the engine needs to run fast idle is only a little bit more that the amount of gas the engine needs to idle.

Simon

Thanks LPGc - I didn't come across the errors on diagnostic so thought it was my fault but perhaps the software does not include it. The current normal mode is that it refuses to go across to gas when I press the button -green light blinks for a while then alarms - often straight away. Having said that, yesterday I took out the liquid filter and solenoid plunger and it went across to gas and I drove around the hill here for 10-15 mins on gas at fairly slow speeds (idling was not noticeably a problem) and was just congratulating myself on fixing it. Then, just as I was explaining to a puzzled Spanish neighbour why he could see me driving pointlessly over the mountains with next to no clothes on, the alarm went (idling at the time) and I came back very disappointed. But this could point to a faulty AEB025 couldn't it ? I've heard that the reducer tends to let more gas out when faulty if anything.
On the AEB025 The pressure P tube goes to the nearest injector and the vacuum V tube goes to the top plenum? chamber. next to two bigger tubes.

I was going to go over old steps - power the tank solenoid (engine stopped) undo the pipe at reducer to judge if tank pressure is really getting there - only a judgement I imagine it is similar in strength to when disconnecting the adapter filler at the gas station. Then, knowing that the inlet solenoid is not a problem when plunger was removed perhaps it is the reducer or pressure sensor. On my test pics posted earlier you noticed that the pressure fell off as the RPM increased and that it alarmed off up in the 3000 rpm region. More than this I'm stumped.

Right - you will all be relieved to hear that with your help the problem is solved - crossing fingers tightly ! This morning I put 12 volts on the tank solenoid and with the plunger out on the reducer confirmed that there was plenty of gas at the injectors. But I found that gas was leaking from the tube fitting on the injector that leads to the AEB025 Pressure sensor which has been ok for ten years but I must have dislodged it changing the plugs. The problem started then. Also it was never fitted with a spring clip as all the other joints are so was able to leak. The leak must have been sufficient for the pressure sensor to register a low reading and shut off the solenoid. Been on a 30 min road test up and down the hills and so far it is ok. Still have to be sure that the crack on the input solenoid will allow it to work until I can replace it. Thanks to all who have taught me loads about the system - as the car and I are getting older with no hope of a replacement I'm going to need the knowledge.

Fantastic news :)
Welcome to semi-affordable motoring!

Yeh that's good!

Must have been quite a leak on the 4mm pipe. Even without a spring clip or even if you cut part way through that pipe would still expect the pressure sensor to read system pressure.

Simon

Well the pipe is not in too bad condition and all I did was rob a spring clip from the vacuum pipe on the plenum chamber and it is secure and holds ok. It does seem that the loss which one could hear as a slight hiss was enough. When I took the pipe right off to put the clip on there was lots of pressure in it and that startled me but enabled me to confirm that there was good pressure to the injectors. There could still be a something not up to scratch in the pressure sensor but for the moment it works. All this help and having to explore the problem has shown me the steps to take to find out the cause. Anyone having a similar problem I would say - power up the tank and input solenoid, take off the feed into the injector - at least then one can confirm that everything in the line appears ok. The software showed the pressure dropping as I increased the rpm so it was finding its way out at that connector.

Only thing is, at higher rpm in neutral the engine manifold pressure will be lower than at normal idle speed, and since gas pressure is relative to manifold pressure gas pressure should be lower at high idle speed so less gas should escape from any leak.

Yes but perhaps heat and vibration was enough to open it up more. Anyway, been on quite arduous journeys today and it is performing as normal. Steve at Jaymic pointed out that my readings which I posted showed that system was set for 8 cylinder in line instead of V8 which is shown by the number of boxes for Tin gas and Tin petrol which should be 2 each and this is set by the lambda screen and selecting 2 instead of 1. This has probably been the case since installation - Also he suggested that reducer pressure setting of 1.1 should be 1.4 bar. In fact he said the system needs a re MAP calibration but not to worry if it is ok with the above changes. He confirmed that it should be possible to blow through the inlet filter which I was unable to do so am leaving it out until replacement arrives. So pleased to have it running on gas again !

One other thing - do you think I should select the option 'Start on gas with hot engine' - with the short journeys here and the heat in Spain it would save some petrol or are there other considerations ?

I'd give it a try, although hot engine refers to coolant temp rather than ambient temp, I'm sure your engine will cool down more slowly than in the UK! It's really for situations where you're stopping and re-starting a hot engine. It'll save you some fuel but it's hard to say how much.

It may not start too easily on gas when hot, or if it does will almost certainly crank for longer. Try it but if it doesn't start up immediately, then leave it starting on petrol but change the changeover delay to as short a time as the software will allow.

Thanks Morat - I think it makes sense for me because I shop and stop at about 4 places on the coast and the air temp is around 34 so the engine does not cool very quickly - at least the system sounds like it is clever enough to decide if I give it the option. A story (shows my stupidity) - parked in an underground car park to have a meal out and when I came back car would not start. Realised there was something wrong like fuel and had to leave the car - get a lift home then next day a recovery vehicle - not easy in the car park only about 10 cm clearance and explain to parking man that I had been unable to move car - he let me off with a lower park charge ! Taken to my favourite garage guy who announced the petrol pump had had it. Then I remembered that I could have started it on gas and saved all the expense and agro - ..............................

Noted-both - I see that the delay is 40 seconds - not long but the other setting that is involved is presumably the 1600 rpm changeover and on these short stop trips it sometimes takes a while to exceed 1600 - I suppose I could blip the throttle ! but use more petrol again !

Expect you guys have been through all this years ago ..............

I've got mine set to changeover at 1,200 rpm and 1 second changeover. Admittedly it's a different system but there's nothing to stop you trying the same. On mine, I start the engine, the revs rise as it fires and it changes over as the revs drop down again.

Morat wrote:

I'd give it a try, although hot engine refers to coolant temp rather than ambient temp, I'm sure your engine will cool down more slowly than in the UK! It's really for situations where you're stopping and re-starting a hot engine. It'll save you some fuel but it's hard to say how much.

I'd have thought this wouldn't matter too much with an injected system, I can see why it would be different with a single point/mixer. Suck it and see, I guess?

Slightly different point - how does one get a picture to show on here ? I know there is Pic add button but that seems to require an upload to an external picture site like imgur and then it shows only as a link. But some I have seen here appear on the screen direct.

Upload the picture to Imgur and paste the Direct Link (second one down that ends in jpg) into the box. It will then appear in the post.

Ok thanks - dog walking time now on the mountain - 35 degrees - sun just dipping.![Just testing pic](http://i.imgur.com/1Okt6Hg.jpg

Somehow you managed to chop the end off the command, after the url to the picture, there should be further text that then closes the brackets.

Like this

Ah yes - I deleted the bit in brackets which said 'picture title' because I had the same at start of link. Thanks - now I have another puzzle which will exercise the best of you. Just been trying to make some changes with the diagnostic software as suggested by Steve i.e. Reducer bar was reading 1.1 - he said change to 1.4 which i did but as soon as I click on next bit to change it reverts back to 1.1 . This happens with all the settings I tried to change except the 2 lambda setting which has shown on all screens. What am I doing wrong ? Tried with engine off - same thing. The diagnostic lead was well and truly chewed by the rats and I repaired it - I think - it works in other ways but perhaps some vital bit is not connected ? Or am I missing something simple here ? You can see the sand and dirt problem here in Spain in my engine compartment !

Having queried the problem with change of data I've now been told that it is necessary to press the 'Enter' key on the laptop before moving on to the next setting - just didn't think of that !