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 Post subject: Delayed Start
PostPosted: Wed Jul 20, 2016 4:32 pm 
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Hi all,
I was looking for a thread about delayed start but i wasn´t able to find it.
A car (Renault Megane) was converted with Tartarini EVO01 system. Sometimes the engine delays to start.
+12V wire is connected to injector positive wire. It doesn´t happen always....

Any idea or tell me a thread about this please

Thanks

Fabian


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 Post subject: Re: Delayed Start
PostPosted: Wed Jul 20, 2016 5:15 pm 
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Delayed start or delayed switch over?

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 Post subject: Re: Delayed Start
PostPosted: Wed Jul 20, 2016 9:40 pm 
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Gilbertd wrote:
Delayed start or delayed switch over?

Hi Gilbertd,
at the start time. Sometimes maybe twice or three times per day when I switch on the engine doesn´t start. After two or three attempts it does.
I´ve tried taking the lpg fuse off and there was no problem.
I don´t know if at this moment the start signal is lost...
Thanks in advance for your help


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 Post subject: Re: Delayed Start
PostPosted: Wed Jul 20, 2016 10:39 pm 
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It sounds more like a starter motor problem than anything to do with the LPG system - don't forget that most LPG systems still start on petrol so if it's not even turning over then chances are it's the starter motor and/or associated circuits or maybe the inhibitor switch if it's an automatic.
Often once the brushes get worn in a start motor, operation becomes erratic and it could be that it was working fine when you pulled the LPG fuse and would have worked even if you left the fuse in.

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 Post subject: Re: Delayed Start
PostPosted: Thu Jul 21, 2016 1:53 pm 
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Leaking gas through the vacuum line into the manifold is more likely (displacing the air that should be in there in the process and ending up with too rich a mixture to start) - Is is any different if you switch to petrol before stopping (give it a minute or so on petrol before shutting off the engine first to clear any residual pressure).

If its just cranking and failing to start that is, which is the impression i get.

Other way to prove if this is at fault is to remove the vacuum line from the vapouriser and put the open end into some water (the other end of same line being connected to the vapouriser). With lpg switched on if your getting bubbles thats a sign your leaking gas. You may also be able to smell/see it to some degree depending on how much if any is leaking, but it can be hard to be certain.


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 Post subject: Re: Delayed Start
PostPosted: Thu Jul 21, 2016 9:36 pm 
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LairdScooby wrote:
It sounds more like a starter motor problem than anything to do with the LPG system - don't forget that most LPG systems still start on petrol so if it's not even turning over then chances are it's the starter motor and/or associated circuits or maybe the inhibitor switch if it's an automatic.
Often once the brushes get worn in a start motor, operation becomes erratic and it could be that it was working fine when you pulled the LPG fuse and would have worked even if you left the fuse in.

Hi Dave,
thanks for your reply. I agree with you that most lpg systems start on petrol but my concern is if the car runs on petrol it stars well (i´ve tried it during one week) and it runs and stops on lgp sometimes the engine delays its start


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 Post subject: Re: Delayed Start
PostPosted: Thu Jul 21, 2016 9:53 pm 
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Brian_H wrote:
Leaking gas through the vacuum line into the manifold is more likely (displacing the air that should be in there in the process and ending up with too rich a mixture to start) - Is is any different if you switch to petrol before stopping (give it a minute or so on petrol before shutting off the engine first to clear any residual pressure).

If its just cranking and failing to start that is, which is the impression i get.

Other way to prove if this is at fault is to remove the vacuum line from the vapouriser and put the open end into some water (the other end of same line being connected to the vapouriser). With lpg switched on if your getting bubbles thats a sign your leaking gas. You may also be able to smell/see it to some degree depending on how much if any is leaking, but it can be hard to be certain.

thanks Brian for your advice.
mmmmmmmm it sounds to me that it may be the reason. I´ll prove your assumption...
So you mean that could have a lpg leaking inside the reducer through the vacuum line? or some lpg injector remains open after switching off


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 Post subject: Re: Delayed Start
PostPosted: Thu Jul 21, 2016 9:59 pm 
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Fabian wrote:
Brian_H wrote:
Leaking gas through the vacuum line into the manifold is more likely (displacing the air that should be in there in the process and ending up with too rich a mixture to start) - Is is any different if you switch to petrol before stopping (give it a minute or so on petrol before shutting off the engine first to clear any residual pressure).

If its just cranking and failing to start that is, which is the impression i get.

Other way to prove if this is at fault is to remove the vacuum line from the vapouriser and put the open end into some water (the other end of same line being connected to the vapouriser). With lpg switched on if your getting bubbles thats a sign your leaking gas. You may also be able to smell/see it to some degree depending on how much if any is leaking, but it can be hard to be certain.

thanks Brian for your advice.
mmmmmmmm it sounds to me that it may be the reason. I´ll prove your assumption...
So you mean that could have a lpg leaking inside the reducer through the vacuum line? or some lpg injector remains open after switching off


Could be either of those causes - they would both have the same sort of effect. You would need to investigate yourself to tell for sure, easiest way to start with is just switching back to petrol for a short while before switching off. You need to leave it long enough to allow any remaining pressure to drop off (30 seconds should be enough, may need a few times of trying to prove or disprove it).


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 Post subject: Re: Delayed Start
PostPosted: Fri Jul 22, 2016 12:01 am 
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Joined: Sun Aug 09, 2015 12:45 am
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Fabian wrote:
LairdScooby wrote:
It sounds more like a starter motor problem than anything to do with the LPG system - don't forget that most LPG systems still start on petrol so if it's not even turning over then chances are it's the starter motor and/or associated circuits or maybe the inhibitor switch if it's an automatic.
Often once the brushes get worn in a start motor, operation becomes erratic and it could be that it was working fine when you pulled the LPG fuse and would have worked even if you left the fuse in.

Hi Dave,
thanks for your reply. I agree with you that most lpg systems start on petrol but my concern is if the car runs on petrol it stars well (i´ve tried it during one week) and it runs and stops on lgp sometimes the engine delays its start


AH-ha! I misunderstood the problem you have - given i now realise the problem i would think Brians answer is the most likely

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 Post subject: Re: Delayed Start
PostPosted: Fri Jul 22, 2016 11:40 am 
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The other way you may be able to diagnose the problem is using the software/lead if you have them, monitor the gas pressure when its switched off (it should hold pressure, if it drops away its letting gas go somewhere). Depends what you find easier or more reliable. This won't tell you where its going of course though.


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 Post subject: Re: Delayed Start
PostPosted: Sat Jul 23, 2016 7:14 pm 
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Joined: Wed Sep 29, 2010 5:01 pm
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Location: Yorkshire
Agreed it is most likely a gas leak into the inlet manifold will be to blame (reducer vac port or injector) but there are other potential reasons... E.g. Fuel trims can drift while running on LPG if calibration is incorrect - some ECU's apply fuel trim data even during engine start and full throttle conditions, so this could cause over lean / over rich cranking mixture on petrol. After running on LPG, does the engine run properly when started but still cold or does it run better if you've driven it on petrol for a while before turning the engine off?

Simon

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 Post subject: Re: Delayed Start
PostPosted: Mon Jul 25, 2016 6:57 pm 
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Brian_H wrote:
The other way you may be able to diagnose the problem is using the software/lead if you have them, monitor the gas pressure when its switched off (it should hold pressure, if it drops away its letting gas go somewhere). Depends what you find easier or more reliable. This won't tell you where its going of course though.

Thanks Brian, as soon as I get the interface cable and software i´ll try it


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 Post subject: Re: Delayed Start
PostPosted: Mon Jul 25, 2016 8:47 pm 
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LPGC wrote:
Agreed it is most likely a gas leak into the inlet manifold will be to blame (reducer vac port or injector) but there are other potential reasons... E.g. Fuel trims can drift while running on LPG if calibration is incorrect - some ECU's apply fuel trim data even during engine start and full throttle conditions, so this could cause over lean / over rich cranking mixture on petrol. After running on LPG, does the engine run properly when started but still cold or does it run better if you've driven it on petrol for a while before turning the engine off?

Simon

Hi Simon, thank you for your advice.
The car run very well on lpg before it run on petrol or lpg. If the engine is cold and switch over to lpg there is no problem with it.
You mean that petrol ecu can be modified by lpg ecu? in both cases you commented the car run on lpg well. The only problem is at the start moment. In case of lpg ecu changes petrol ecu this problem would appear everytime i switch the engine on?


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 Post subject: Re: Delayed Start
PostPosted: Mon Jul 25, 2016 9:21 pm 
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Fabian wrote:
Brian_H wrote:
The other way you may be able to diagnose the problem is using the software/lead if you have them, monitor the gas pressure when its switched off (it should hold pressure, if it drops away its letting gas go somewhere). Depends what you find easier or more reliable. This won't tell you where its going of course though.

Thanks Brian, as soon as I get the interface cable and software i´ll try it


If you don't have the cable at the moment pull the hose off and see if anythings coming out, much harder to test injectors for sticking open, though you may be able to remove hose from them in the same fashion and check for pressure there if you can get to them. The other test given (switch to petrol before switching off engine) should help confirm the likely cause without any disassembly.

You might want to check the current pressure set on the system before swapping any parts though, so the lead would be useful before too much is done anyway.


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 Post subject: Re: Delayed Start
PostPosted: Sun Aug 07, 2016 4:38 pm 
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hI there,
just to tell I couldn´t comment yet because the customer is on holidays. As soon as I can test I´ll post to close the thread


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 Post subject: Re: Delayed Start
PostPosted: Tue Jan 10, 2017 12:54 pm 
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I have a similar problem with my old carburettor VW T25, a very old system which is usually very reliable.
Currently my problem is that it takes a long time to start,perhaps 10 to 15 seconds of turning the engine over. I have never needed to switch to petrol to start, not even when the temperature has been minus 10 and when it fires up there is no misfiring or rough running which leads me to wonder whether a valve has failed and gas is having to be bought from the pump (none in the fuel lines) but I am guessing.
Earlier this year I had to take out the petrol tank and replace the petrol pump and I disturbed some kind of Y connector with a knurled brass knob on it, I have no idea what it is and I don't know what make the system is. Any insights appreciated.


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 Post subject: Re: Delayed Start
PostPosted: Tue Jan 10, 2017 5:39 pm 
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Location: Yorkshire
If the knurled brass knob you mention is an LPG component it will be the inline gas flow adjuster, adjusting this affects mixture (particularly during driving rather than at engine idle, during starting it will affect mixture too).

Other than that the cause of your recent troubles are anyone's guess, there are so many factors that could bring on difficult starting on gas including the recent cold weather.

Simon

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 Post subject: Re: Delayed Start
PostPosted: Tue Jan 10, 2017 5:45 pm 
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To rule out whats said as a possible cause above (gas leaking into the inlet) let it run a couple of minutes on petrol and shut it off, then try to start again later, if it starts then its likely to be leaking gas into the mainfold. Causes of that depends on the system type fitted, repair of it would depend on the system in question.

Being a carbed vehicle its probably a single point system though. It might help to identify your system - photos of the bits you can find (changeover switch, under bonnet bits etc) may help here. If you can get to the brass knob bit it may help to see that, it could be a power valve indicating an older type single point system and you may have adjusted it by accident? Where is the brass bit located?

Might be best to start a new thread with that info though and description of the problem. my reply crossed with Simons above, New thread with more info may give you an answer.


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 Post subject: Re: Delayed Start
PostPosted: Wed Jan 11, 2017 3:23 pm 
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Many thanks to both of you above, gas flow adjuster is useful info. I do all of the maintenance on my old van but the LPG system is a mystery best left to those who know better. I have been all over the engine and I've never seen any makers mark on the LPG but if a single point injection means the LPG is injected throug a collar that sits on top of the carb then that s what I have.
Having said that, yesterday it started after three seconds turning over the engine but this morn it took ten, and it had been left for three days or so when I went to it yesty. Strange.

Thanks for your help but I was expecting the It could be one of many factors answer.


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 Post subject: Re: Delayed Start
PostPosted: Wed Jan 11, 2017 5:30 pm 
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You've got a single point system but is it open or closed loop? In the hose from the vaporiser to the mixer (the collar bit on the carb), will be an adjuster, is it a manually twiddleable knob or is it an electrically operated thing with wires coming from it?

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'96 Saab 900XS, AEB Leo, sold
'93 Range Rover 4.2 LSE, Lovato LovEco, sold
'98 Ex-Police Range Rover 4.0, Singlepoint AEB Leo, my daily motor
'97 Range Rover 4.0SE, eGas multipoint, a project.....

Proud to be a member of the YCHJCYA2PDTHFH club.


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