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[highmiler]

I have had this car over 15 months and now it wont start straight away from cold it takes about 3 minutes to get it going just constantly turning over the engine.
I have had all the following replaced Battery/Alternator/Crank shaft sensor/Cam shaft shalf sensor/Engine core temp sensor/Airflow meter/Air temp Sensor/ignition pack/plug leads/Spark plugs/Petrol pump relays.

This has not cured the problem once the car is warmed up i have no further problems until it cools off for more than 4 hours readings take from the brain of the car only suggest that the injectors are low on power when in LPG running no codes are present running on petrol anybody got any ideas only my neighbours are now complaining as i work early mornings and tend to wake them up.
Highmiler

[tunnie]

Hi,

Welcome to the Forum  

My thoughts are fuel pump, I assume the car starts on Petrol then transfers to LPG once warm?

Someone called Martin Imber a member here, would be best to comment on this he has a 2.6V6 LPG converted Omega..

[JamesV6CDX]

If it should be firing up on petrol, then the LPG system should be irrelivent.

Martin may correct this, I am GUESSING, but is the gas changeover device working? If it's trying to start on LPG instead of petrol, then it will be a hard start.

When the car is warm, will it run OK on Petrol??

[Taxi_Driver]

That is correct it should be starting on petrol....then switching to lpg.....i dont think it would start on lpg from cold.....thats what the vapouriser is for to convert the liquid lpg to a gas...and only can do that if the water temp is around 40C.

To definately make sure its trying to start on petrol and not a fault with the lpg......pull the fuse on the lpg system.....this will make it only use petrol...

My initial thought is petrol injectors are partially blocked from little use..if its not a fault with the lpg system..tho im sure Martin will be able to advise more  

Do you know what lpg system is fitted?

[highmiler]

Hi
Not sure what system it was fitted at the factory before registration the injectors should be clean as i run it quite a lot on the petrol as i am a taxi it only does about 200 miles on gas and we are a bit short on LPG stations around where i work so most days it will run 20/50 miles on petrol.

Where am i likely to find the fuse inside or under the bonnet.
highmiler

[tunnie]

That is correct it should be starting on petrol....then switching to lpg.....i dont think it would start on lpg from cold.....thats what the vapouriser is for to convert the liquid lpg to a gas...and only can do that if the water temp is around 40C.

To definately make sure its trying to start on petrol and not a fault with the lpg......pull the fuse on the lpg system.....this will make it only use petrol...

My initial thought is petrol injectors are partially blocked from little use..if its not a fault with the lpg system..tho im sure Martin will be able to advise more  

Do you know what lpg system is fitted?

For some reason i clean forgot your was LPG!  

Anyway as TaxiDriver says pull the fuse. You say that the LPG was fitted at the factory? If that's cause you got yourself a rare find, I have seen factory fit Vectras with LPG but never an Omega!

As for the fuse, not sure as its factory fit it must be labled in the box under the steering wheel.

[TheBoy]

You say that the LPG was fitted at the factory? If that's cause you got yourself a rare find, I have seen factory fit Vectras with LPG but never an Omega!

Not really - LPG was a factory option on 2.0

[Paul M]

That is correct it should be starting on petrol....then switching to lpg.....i dont think it would start on lpg from cold.....thats what the vapouriser is for to convert the liquid lpg to a gas...and only can do that if the water temp is around 40C.

This is actually an urban myth, a correctly set up LPG system with good coolant flow and (importantly) enough anti-freeze can start and run from cold with very few problems. You don't actually need to heat the vapouriser, just provide enough energy for evaporation of the liquified gas. Cold water can provide this energy, as long as it's constantly flowing and has enough anti-freeze to prevent freezing which obviously stops the flow!

Often there isn't sufficient flow for the cold water to provide the required energy (perhaps depending on relative location of the thermostat or heating circuit) or it's just poorly plumbed in, as is the case for my Omega which takes its supply from the header tank(!) something I may rectify when I replace the heater bypass valve. Hence my Omega won't run on gas until it's warm, but I've driven several dual-fuel cars that can start on gas and run just as well as petrol (possibly even better as you don't need cold enrichment) even when it's freezing outside.

The other reason for starting on petrol is that it ensures the petrol system is regularly being used, if a car is constantly run on gas the petrol injectors or pump may develop problems through lack of use.

[Chopsdad]

Hi
Not sure what system it was fitted at the factory before registration the injectors should be clean as i run it quite a lot on the petrol as i am a taxi it only does about 200 miles on gas and we are a bit short on LPG stations around where i work so most days it will run 20/50 miles on petrol.

Where am i likely to find the fuse inside or under the bonnet.
highmiler

Well it isn't likely to be one of these http://www.omegaowners.com/forum/YaBB.pl?num=1161602008.  

[Martin_1962]

Two possible problems

1) Evaporation and clogging, run Redex or similar through the injectors, use Shell Optimax - LPG cars easily clog the petrol injectors.

Also switch to petrol for the last 20 seconds to refill them

2) Cut injectors dodgy connectors, the injectors are cut off by the LPG ECU and either the Simtek ECU drives an emulator box, or are emulated within the LPG ECU, most modern systems are ECU emulated and use the signals to drive the LPG ECU.

Here I would look for water ingress in cabling or a loose connector. You will find extra wires on the petrol injectors, follow these leads and see where they join the cars own loom. Also check where the cut injector loom joins the LPG ECU loom.

Failing that I would suggest plugging car loom into injectors and see how it starts, well means LPG loom problems, bad means injector or car loom problems

[Taxi_Driver]

If your are still having probs after trying the above suggestions.....as its a factory fitted system....try giving these peeps a call www.millbrook.co.uk They probably fitted the LPG to your omega in the first place.
They were very helpful when i called them about a problem with my veccyC dual fuel.
If they are too far away to visit, they can tell you which vx dealers near you that have been trained by themselves....as apposed to vx dealers that havent but still have the lpg diag kit. (which you dont want to visit!)

[Craig_R]

12a. LPG Starting Procedure

(Petrol injected engines with single point closed loop conversion.)

It would be impossible for me to count the times I hear this statement -
"It doesn't start very well on gas......"

It is one of the most meaningless things anyone can say about a converted vehicle.

For clarity, most systems fitted in Britain NEVER start on gas, they start on Petrol every single time. It does not matter whether the fuel choice switch is set to the Petrol or Gas position, the system will only switch over to gas from Petrol if gas is selected and the changeover criteria are met (normally engine RPM reducing from 15 - 1600 and engine coolant temp. of 30C or so). When these facts are considered it is plain that no converted engine actually starts on gas (unless the changeover requirements are modified or the system is cheated with and emergency start procedure).

As for "It doesn't start very well on gas......" here is what really happens -

If the engine is stopped from gas running some unused gas will remain in the inlet manifold. When the engine is cranked for restarting with the switch in the gas position PETROL will be injected, but the remaining gas will also be inducted. Both fuels will be drawn into the cylinders, making the Fuel / Air mixture too rich for the engine to start.

This is only a temporary problem, further cranking will lean the mixture back down to Petrol only, the engine will start and a subsequent switch over to gas will occur if and when 15 - 1600 RPM are attained and then reduced.

If this slower start (actually the result of Dual fuelling) is to be avoided there is one very simple remedy - If you have made a journey running on Gas, Switch back to Petrol and run for one minute before stopping the engine. Dual fuelling will then be avoided and normal Petrol starting will be regained.

For the trouble shooter, once this passage has been read and thoroughly understood it will also clear up some other misconceptions about converted vehicles.

As an example, if someone says that their car will not start on Gas or Petrol, it will be clear that the vehicle has a basic problem with ordinary Petrol operation and its inability to start is nothing to do with any gas conversion fitted (as long as all inlet air pipes and inlet manifold connections are good).


HERE IS A LINK TO THE PAGE FULL OF INTRESTING TIPS FOR LPG CARS

http://www.go-lpg.co.uk/hints.html


Craig

[highmiler]

Hi There
Thanks for the reply I normally drive the last half a mile or so on petrol only before i park up for the night but the damm thing still don't start .
Today i tried seeing if the rail was full of petrol and it came out from the valve ok still didn't start though have now ordered a pressure vale for the fuel rail as i have replaced just about every thing else new fuel filter was fitted a short time ago.
highmiler

[Martin_1962]

Have you put injector cleaner through yet?

[highmiler]

If your are still having probs after trying the above suggestions.....as its a factory fitted system....try giving these peeps a call www.millbrook.co.uk They probably fitted the LPG to your omega in the first place.
They were very helpful when i called them about a problem with my veccyC dual fuel.
If they are too far away to visit, they can tell you which vx dealers near you that have been trained by themselves....as apposed to vx dealers that havent but still have the lpg diag kit. (which you dont want to visit!)

Been in touch with millbrook people and arranging to get it to Slinfold West Sussex for there trained people to look at it