Has anyone had a problem changing from lpg to petrol? My V8 Disco starts and runs well on lpg but will not start or changeover to petrol from lpg even when warm. I have changed the fuel filter, checked the solenoid and the changeover switch and all appear fine. I am beginning to suspect the fuel pump in the tank but need to know how this can be carried out. Has anyone had a similar problem? Any advice would be appreciated.
LPG / Petrol Changeover.
- Thread starter AndyV8
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Langers
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Mine doesn't like going from LPG to Petrol, but that is only because it's carbed. The LPG tends to freeze up the carbs and I have to get out and give them a wiggle before it will run smoothly on petrol. To get around this, I just don't switch it onto Petrol. Ever. 
captainbeaky
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Try starting it on petrol.
You should hear the petrol pump whirring as soon as you turn the ignition on.
On rangies, there is a vulnerable connector back there, on one of the rear crossmembers that can get corroded.
You should hear the petrol pump whirring as soon as you turn the ignition on.
On rangies, there is a vulnerable connector back there, on one of the rear crossmembers that can get corroded.
fireman-andy
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you should be starting on petrol and only switching to lpg once warmed up .
At least this is the case for injected systems.
At least this is the case for injected systems.
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That is done automatically on most of the multipoint systems, as all they seem to do is to transfer the injector drive to the gas valve drive, and keep all the sensors running as for petrol.
We leave the gas/petrol switch on LPG, but it will invariably start on petrol, even if you stop it on gas and immediately re-start, it still does the the purging of the gas valve block etc.
Peter
All dual fuel (gasoline/LPG) start on petrol. Carburetted systems start on petrol and imediately switch to LPG unless you overide with the switch on your dashboard. Sequential systems sart on petrol and change to lpg at predetermined sttings. There are 3 paramiters affecting the change over point - gas inlet temperature, engine speed and whether change over is set for engine speed rising or falling. There are many other aspects which affect the running (performance) of the system but those 3 parameters affect the change over and can only be accurately assessed and adjusted when connected to the relavent manufacturers set-up software.
terratology
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Langers
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terratology
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Bollox......in the cold weather spell my rangy would refuse to start on gas as it was too cold so I would have to 'manually' i reiterate 'manually' switch it over to petrol for it to start. Explain that one then oh and for the fact that i can also start it when there is no petrol in the tank.
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Ah never mind terratology, perhaps when you grow up and have maybe had the opportunity to have installed as many as I have you may begin to understand. In the meantime, I suggest you get your system checked and have the reason for poor cold starting rectified. Any system should start instantly whichever mode it is in. I would suggest that somebody has interfered with the safety management system of your car perhaps it wasn't properly installed or maybe some smart alec thinks he can save money by bypassing the safecty lock-out and avoid paying for petrol start - anyway for your own safety and that of other road users get it checked by a competant installer - oh and it may affect your insurance payout if after a fire they discover that the system has been modified or not properly maintained. I don't intend to prolong this discussion beyond this response. I just wish you well for the future
Jon14
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Not wanting to fuel any fire, but mine (1999 Disco2 V8 - LPG fitted when new) definitely starts on petrol no matter what position the G/P switch is in. From a cold start, it runs on petrol for a minute or so, then you can hear a very slight 'clunk' as it changes over. The lights on the switch indicate which it's running on too.
Don't have any issue going from LPG to petrol on the move though.
Don't have any issue going from LPG to petrol on the move though.
GasFiredDisco
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Ok lets clear this up.
The knowledge I am passing on is from the local Autogas center and the guy who we bought our Discovery off, that man has installed more than 3000 systems on various vehicles - the discovery was his own vehicle until it was replaced with a D3 hence us buying it.
So for once I wont be talking utter bull****!!
Carb systems can start straight from LPG as there is nothing computer controlled.
EFI systems MUST start from on petrol regardless of the LPG being muti-point or single-point as the default for the system is petrol, in most system it uses about a tea spoon full of petrol to start and changes to LPG almost immediately. As SuperPete has said, any system should start instantly (well as instantly as a LR can do) regardless or what mode it is in, if it doesn't it needs a service by a LPGA approved person as something isn't right - LPG and something not right isn't a good combination.
If you don't want to take it from me feel free to ring ANY LPG specialist and they will put you right.
The knowledge I am passing on is from the local Autogas center and the guy who we bought our Discovery off, that man has installed more than 3000 systems on various vehicles - the discovery was his own vehicle until it was replaced with a D3 hence us buying it.
So for once I wont be talking utter bull****!!
Carb systems can start straight from LPG as there is nothing computer controlled.
EFI systems MUST start from on petrol regardless of the LPG being muti-point or single-point as the default for the system is petrol, in most system it uses about a tea spoon full of petrol to start and changes to LPG almost immediately. As SuperPete has said, any system should start instantly (well as instantly as a LR can do
) regardless or what mode it is in, if it doesn't it needs a service by a LPGA approved person as something isn't right - LPG and something not right isn't a good combination.If you don't want to take it from me feel free to ring ANY LPG specialist and they will put you right.
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vougese39
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from an insurance point of view you nolaonger have a cert of compliance for the gas system so if you have a problem your insurance in non and void! does it run ok on petrol do you run it with a very low amount of petrol in it? as the pump is called asubmerised pump by it's name it means it needs to be submerised as the petrol is the lubricant and cooling agent if it is ran on gas it is still working with little or no fuel it will run dry and wear out very quickley thus fubard!
Assuming that your comment is directed to Langers and Terratology, aren't you jumping to conclusions? Neither of them said that their systems have been tampered with to avoid running on petrol, simply that they don't! Terratology stated that his switch provides either power to the fuel pump or to gas so when he is running on gas the fuel pump, whether submerged or external, is not running so what's the problem.
For the record, my carb based system which was installed exactly in accordance with the manufacturers instructions (wiring diagram) definitely switches so that I either have power to the petrol side or gas but not both so how does not having petrol in the tank (or having petrol in the tank but not using it) invalidate my insurance?
Cheers
Chris
Langers
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Agreed, my system also has a two way switch, which allows me to run on EITHER petrol or gas, but there is no automatic switching involved. I do think however that it is a fairly old system. Perhaps newer systems always start on petrol and switch over when warm.
fireman-andy
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this is what mine does (D2 4.0l)even though the lpg system is left switched on. I have to keep petrol in the tank as the fuel pump is always running. The previous owner had to replace it as he kept running the petrol too low and it failed Mine only has a 25l petrol tank and two 40l lpg tanks where the fuel tank was. I think it changes over at 40c . even in the winter it is less than a mile before it changes(I think it is a bit too soon as there is a hesitation on changeover which I dont get in the summer)
I run it on just petrol for 50-100miles about once a month to make sure the injectors etc stay clean , also it allows the ecu to adjust the fuel trims for running on petrol while the engine is hot
Andy
Mogwyth
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Exactly the same as mine.
Now excuse me while I swear my late father had a very early Jeep Cherokee that run on LPG/Petrol which had to be manually switched, it could be started on gas during the warmer weather but as a rule it always run better if started on petrol and ran till it started to warm and then switched to gas.
Bill
terratology
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I know where superpete is coming from, but my system is also an old one being nearly 10 yrs old and nearly due for its tank inspection. Though on my last rangie with lpg that had a 3 way switch on it, left was for start and run on petrol, over to the right was start and run on gas and leave it between the two for it to start on petrol then switch to gas when it hit something like 1500rpm. Theres loads of people on the forums running on gas only and have a manual switch over and for superpete i have not touched any safety valves on my rangie and was only copying the way that you had posted to me. Also my rangie starts first flick of the key from cold on gas, i was actually referring to it starting in the 3-4 freezing days we had around about xmas time as you should know that lpg does not like very cold temperatures hence the water pipes running through the vaporiser.
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