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 Post subject: LPG warm start problems
PostPosted: Fri Apr 21, 2017 2:50 pm 
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I've got a 2003 Range Rover L322 with a BRC Sequent 56 LPG system which takes longer to start when warm and it has previously been running on LPG. It takes about 5 or 10 seconds to start when it has been running on LPG. If I switch the LPG system to petrol before starting it still struggles to start, but if the car has been running on petrol before being switched off it's fine and starts instantly. When it does eventually start it runs lumpy for a few seconds. Apart from the starting problem the LPG system seems to be perfect. Any ideas what I should check/replace?

Also can anyone point me in the direction of what cable to buy and where I can find the software to talk to this ECU?

Thanks.


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PostPosted: Fri Apr 21, 2017 3:15 pm 
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It could be down to either a leaking injector or leaking vapouriser filling the manifold with gas - if you can find the vacuum line to the vapouriser pull it off, plug the end that goes to the engine to keep it running and see if you have gas leaking from the vapouriser vacuum connection (it may be more visible by putting a piece of the hose into water with the other end connected to the vapouriser then looking for bubbles if its a small leak). Alternatively you may smell lpg when you've stopped the engine, if this is the case its leaking from somewhere, and the symptoms would indicate its filling the manifold. You may be able to detect in the same fashion with the injector hoses if you can get to them (or if you can monitor pressure, if it drops slowly over time once switched to petrol this would indicate a leak).


http://lpg-kits.com/ lists a compatible cable, Tinley tech are now the UK BRC distributor so may be able to assist with a cable? You should be able to do most of the above without the cable though, and its unlikely the cable will help just yet though they can be useful to have.


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PostPosted: Fri Apr 21, 2017 3:56 pm 
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Brian described a likely reason for the struggling to start. The actual problem would then be that gas escapes into the inlet manifold of the engine so that when you come to start it the engine gets no air (gets gas instead) until the engine has pumped the gas out of the exhaust and sucked new air into the inlet manifold. The same situation would arise if you had an LPG injector that allowed gas to leak into the inlet manifold when the engine was stopped.

Other reasons could be 2 if LPG calibration isn't correct, as then the engine gets the wrong amount of fuel during cranking and when first run on petrol. 3 if this is a Jag engine'd L322 it should be fitted with a petrol fuel return that will only be active when running on LPG, if this fuel return allows petrol pressure to be lost after you've switched off the engine the pressure will have to build again before the engine will start.

I wouldn't bother trying any cable for BRC except the proper BRC branded cable, which Tinleytech should be able to supply along with the software. I would advise caution before changing settings in BRC software although it's maybe more difficult to mess things up totally with Sequent56 than with other BRC systems, even so I would advise sticking to just the data monitoring screen and maybe adjusting petrol to gas changeover settings. The data monitoring screen might reveal LPG pressure falling away when you switch to petrol, which would then indicate gas leaking under the bonnet somewhere... and given your symptoms most likely into the inlet manifold due to leaky reducer or injector.

Simon

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PostPosted: Sat Apr 22, 2017 1:15 pm 
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Bingo, gas is coming from the vacuum line. The vaporiser says BRC MTM Italy Genius Max. Would a repair kit like the following fix this issue: http://tinleytech.co.uk/shop/lpg-parts/ ... t-genuine/

There seems be two Genius Max repair kits listed on Tinley Tech, the one linked BRC black genius max so I assume that's version I need since I have a black one. Anything to be aware of when repairing them or is it all pretty much straight forward?


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PostPosted: Sat Apr 22, 2017 9:43 pm 
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jacckk wrote:
Bingo, gas is coming from the vacuum line. The vaporiser says BRC MTM Italy Genius Max. Would a repair kit like the following fix this issue: http://tinleytech.co.uk/shop/lpg-parts/ ... t-genuine/

There seems be two Genius Max repair kits listed on Tinley Tech, the one linked BRC black genius max so I assume that's version I need since I have a black one. Anything to be aware of when repairing them or is it all pretty much straight forward?


Repair kit should work, though bear in mind it won't be as good as a new vapouriser. Simon will be able to advise better on that front and which kit you will need, Alternatively take some photos of the unit and ask Tinley if they can advise if you don't get an answer on suitability from here.


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PostPosted: Sat Apr 22, 2017 9:46 pm 
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Why won't it be as good as a new unit out of curiosity? Does a repair kit not replace everything that wears?


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PostPosted: Sat Apr 22, 2017 10:05 pm 
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no its only the rubber bits - matters more on some units than others, but on some metal bits (jets and springs amongst other things) will suffer wear.

Given that its running OK you will probably be fine with the repair kit, provided you can get the thing apart. Would need someone more experienced with your unit to be able to tell (old units getting screws to come out etc can make life difficult as they will corrode in place a bit - some worse than others).

Will probably be fine if its not been apart before, most of the more modern units are simpler than the older ones used to be, plus a lot of the issues have been designed out that would have been found previously.


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PostPosted: Mon Apr 24, 2017 12:03 pm 
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Agreed with all Brian's points.

Yes it'll be the correct repair kit as long as yours is the square Genius Max reducer. Since your only problem is likely just to be a leaking diaphragm would expect the repair kit to be all you need to fix it. This model of reducer isn't the easiest or the hardest to fit new bits in.

Simon

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PostPosted: Tue Apr 25, 2017 8:15 pm 
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I received the repair kit from Tinley Tech today. Fitted it and it's fixed. No gas through the vacuum line and starts perfectly after running on LPG.

Thanks Brian and Simon!


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PostPosted: Wed Apr 26, 2017 12:00 am 
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Good to know you've got it sorted. Luckily you noticed before it got much worse too.


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