Little nut that holds the coil in place. Take that off, slide the coil off and you will see a hex at the base of the brass bit that the col fits over. The plunger is inside that. To remove the filter, you undo the bolt in the middle of the shiny plate and the filter element is under that. With both removed you will be able to clean it all out. Another word of advice, wear latex gloves. Anything that is in there will be what is known as Heavy Ends. It is a lubricant that is suspended in the liquefied gas and is there to lubricate the delivery pumps. It is a sort of dark brown gloopy stuff and absolutely stinks. If you get it on your hands you will still be able to smell it a week later.

super4 wrote:

Have checked wiring and things I can get to, managed to get 12 volts to the solenoid on the reducer which sort of worked but did not seem as active as the one on the tank - it may be that the connection I was making was not very good. But what I want to ask is - does the pressure come from the simple fact that the gas in tank is under pressure and therefore makes its way to the intake manifold provided solenoids etc allow it or does the pressure get built by the reducer in addition. If the pressure is in the system all through then presumably I have a blockage or as suggested, a solenoid simply not opening ? Is it as simple as that ?

The tank solenoid will likely be a lot louder than the front solenoid because it is on the tank.. Tap the tank with a screwdriver and it will make a lot louder noise than if you tap the front solenoid with a screwdriver. Plungers in solenoid posts do get fouled with crud / heavy ends but if they open at all they usually flow enough to allow the engine to run OK and it's a similar story with filters. But you could rule out both the plunger and the filter by simply removing them temporarily to see if the same happens with them removed. Even if removing them seems to effect a cure (which might point to plunger post or filter problem) the real problem could still be voltage drop when the injectors pulse for longer duration (could still be main power feed issue).

Simon

Thanks LPGc - lots to think about. Once selected to gas it seems to cut off as soon as the changeover at sufficient revs is made. No idling phase. On motorway and roads at any speed it cuts almost instantly. There was one time about two weeks ago when it gave me about 7 miles on the motorway before beeping. It seems more complicated than I imagined. If I loosen the union where liquid comes into reducer and that is under high pressure does that mean that tube in tank is ok on bottom ? I have only done the basic diagnostic tests - I see there is an error screen - does that show more detail than just the readings ? I worry about the wiring and voltages because it was attacked by rats but it has worked for a long time after I repaired it. Campo rats - the price of living in Spain.

Right - with all the help here was brave enough to take out the liquid fuel filter on the reducer solenoid and used all my trumpet blowing powers to try and blow air through it - assuming blowing though bottom hole and blocking the opposite - not a peep !! Seems solid as a rock What should I expect ? So am replacing without the filter to test - we'll see - has been in there for about ten years ! Can't get the solenoid plunger out - the retaining nut has a tiny edge and ring spanner not making enough contact ......

The solenoid has to be energised for it to open but if you are doing that and you still can't blow through it, there's your problem. Replacement can be got from here http://tinleytech.co.uk/product-category/lpg-parts/filtershut-off/lpg-shut-off-valve/?widget_search=yes

I just blew through the filter and it seemed impossible to get air through it - perhaps it is designed only for very high liquid pressure - anyway, I have taken it out and will keep it out - then tested the solenoid which appears to work however I noticed the blue plastic body of the solenoid is cracked - tried the impedance but never sure what I'm doing with my meter. Could not get the solenoid plunger out as the brass keeper nut is very shallow and my ring spanner doesn't make enough contact but I could hear the plunger moving when I put 12 volts on the solenoid with two test wires. Started the engine full of hope but nothing has changed - still won't change to gas.

The filter is just a filter so you should be able to blow through it. A cracked coil on the solenoid is a sure sign it has gone internally short circuit and is not at all well. It may still be capable of doing something but not a lot. Best bet is going to be to replace the filter/shut off valve complete.

One thing you could try to confirm it, is to slacken off the outlet from the filter to the reducer and try getting it to switch over. If you get a blast of gas then both solenoids are opening and allowing it through but I suspect you won't.

The forum must be pretty bored by now of my adventures with the LPG but the knowledge and advice has been amazing - I shall soon be an expert ! Anyway, hoping that everyone learns something from our experiences here's where I'm at - Took the plunger out of the Reducer solenoid (so it would have no excuse not to pass gas) - powered both tank and reducer solenoid with 12 volts so they were technically 'open' (did this after starting car as it would not start when they were connected first) Warmed up the engine - pressed the gas changeover and got a fail as before as per low pressure - switched back to petrol turned off engine. Guessed that this meant the solenoids were ok so started playing with the pressure sensor with no particular plan but as I pulled the tubes and wires around there was a sudden hiss and smell of gas which I traced to the region of the pipes between the matrix and injectors (drivers side) . Every time I moved it a bit I could cause the gas to leak and stop - the pressure was getting quite low by then. I'm guessing that this could be my Low gas pressure problem which in turn closes the solenoids and shows on the diagnostics as low pressure. I remember that this problem only started after I pulled pipes and wires around in a bit of a temper trying to change the rearmost spark plug. So I'm crossing fingers that when i get back to it tomorrow this will be the answer. Now, does anyone know correct size of the fuel hose needed on my zavoli matrix to injectors ? I have some 12mm outer 6 mm inner in the tool box and hope it might do ! Gained so much knowledge from all the helpful advice !

I think it's unlikely that this leak will be cause of the system reading low gas pressure - If the leak was bad enough to have sensor read low gas pressure you'd certainly have known about it before. Also, any leak that you can start and stop by moving pipes probably equates to only a small fraction of the gas that the engine could use if you put your foot down.... so although it might hiss and stink and generally be less than safe, such leak is probably negligible in terms of a proper functioning reducer's flow capability. The one exception would be if you pulled the pressure pipe to the pressure sensor just about all the way off but then you'd smell and hear it.

With the front solenoid guts removed there's still the tank solenoid, so if you create a leak on the vapour side gas will leak for quite a while (until liquid gas between tank and reducer is used up) before dying down.
You can't use petrol hose for LPG.

5mm or 6mm internal diameter pipe between injectors and manifold, 4mm internal pipe between Matrix injectors and pressure sensor.

Simon

To echo what Simon said, and he is a full time LPG installer after all, do not use petrol hose for LPG, it will dissolve it. You must use the proper stuff. Not sure what you mean by matrix and injectors? The injectors are Matrix, that's the brand. There's two different sections to the gas system, the liquid phase, the tank, tank solenoid, fuel line, filter, shut off valve and the first stage of the reducer. This lot all contain gas as a liquid at around 10 bar pressure (roughly 140 psi). Then you have the vapour side, that's the other half of the reducer, a vapour filter (maybe) and the injectors. This lot is full of vapour which, according to your software, is at 1.1 bar. Your software was showing a drop in vapour pressure as the revs went up, the system detects this drop in pressure and assumes you have run out of gas so switches back to petrol. What you need to find out is why is the pressure dropping, Is it because only a limited amount of gas is getting to the reducer, so a problem on the liquid side or is it because there is a leak on the vapour side so there's not enough gas to run the engine and feed the leak. Doubtful I'd say or you would smell a leak that big.

I take the point about hoses for gas - but getting a bit disheartened here. As I said earlier when I started everything in the normal way with a meter on the solenoid supply and pressed button for gas as it reached correct temp and rpm, for a moment the meter showed 12 volts applied to solenoids but instantly switched off/dropped. When I powered the solenoids with separate 12 volts there seemed liquid pressure and gas pressure getting through but at the moment I switched to gas it failed. So is there a problem with the gas pressure sensor or the wiring for it ? I think the thinner rubber pipe from sensor to injector (matrix named thingy) also leaks as the clamp clip is missing from the tube. Is there a way of testing the pressure sensor - can I just apply some air pressure to it from air supply ? If I was in UK I'd just buy a replacement quickly but here it is a week to arrive if one is lucky. The first diagnostic leads never arrived and Tinleytech kindly sent another - Spanish post !!
Just to add - yes the diagnostic did show a drop in pressure as rpm increased - could this still be to do with leak - or faulty solenoid on reducer - have removed the plunger from it. The hiss of escaping gas was quite noticeable which happened when I moved the injector block with the four leads going to the inlet block. It was this batch of leads and tubes that I pulled around to get at the sparkplug change and after this the gas never worked.

A leak at the injector pipe wouldn't cause it not to switch over. Unless it was all leaking out, which you would definitely know about!

So we are back to the pressure sensor ? Or problem with the pick up pipe in tank - although there was some liquid under pressure when I loosened the input to solenoid...

I suppose, if I power the tank solenoid (engine not running) and loosen the input carefully I would be in no doubt that liquid pressure was reaching the reducer ?

Have a look at the number on it. If it is an 013, replace it with the later 025 (and cable adapter) as it will almost certainly be dead. There won't be any pressure in the 4 small pipes from the Matrix injector blocks to the inlet manifold. You should have vapour at 1.1 bar from the reducer to the injector block and the 4 small pipes just go to nozzles fitted in the inlet manifold. If you get a his when you move the injector block, then it is in the feed to the block not in the 4 pipes after it. The injector block is just 4 small solenoid valves that open to squirt gas in to each cylinder.

Hi Gilbert - thanks makes sense but I should add that the pipe from the Matrix injector block to the pressure sensor is missing a clip at the block end and I was able to see bubbles (wetted the connection) from the pipe joint. Might this be sufficient to show low pressure at the sensor ? Did not realise there were solenoids in the Matrix injector. I see you say possible leak in feed to the injector ? I thought it was coming from low down on a pipe into the manifold - hard to hear exactly where but happens when I move the injector !

As a follow up I did download a picture instruction for servicing/cleaning the Matrix injector block. Did not want to have to start that unless needed , but do they get blocked after ten years - what do you think ?

And I have just checked and realise there is a cable going into the block - would a low pressure problem in the injector block be read by the pressure sensor at that stage ?
This system is more complicated than I realised - I suppose the diagnostics does not read injector problems ?

I see on the Zavoli Tech Man software there is an error page which I never reached that includes Gas injectors - should I do this again and see if there is anything showing ?

Matrix injectors are probably the most reliable you can get (which is why they are so damn expensive!) so unless you have been filling it with really poor quality gas and have no filters in there, it is unlikely they will need anything doing to them. They wouldn't cause a drop in pressure anyway, just rough running. The cable going into the block is the feed to the internal solenoids to open the injectors when required. The pressure is before it gets that far. For a leak to be sufficient for you to see a drop in pressure, it would need to be very big, not just a few bubbles. If you can hear gas leaking out when you move the injector block, look at the larger feed pipe rather than the small output pipes. I suspect all your hoses have gone hard with age so aren't going to be good. If I were you I'd start by getting a replacement pressure sensor (assuming you have an 013) and some lengths of replacement hose and clips for it. While changing them you'll probably find the cause of the fault anyway.

super4 wrote:

I see on the Zavoli Tech Man software there is an error page which I never reached that includes Gas injectors - should I do this again and see if there is anything showing ?

All that can show is and electrical problem, if an injector is open or short circuit, not whether or not there is any gas flowing through it or if it is at the correct pressure.

Seems good advice - I should have mentioned that the pressure sensor is the later type AEB 025 - actually shows on the diagnostic pics I think