Passat wont start!

[jasear]

Hi,

I have a dual fuel (LPG converted) Passat Syncro 1997 R reg. It ran out of petrol and I filled it up but the battery went flat as I was repeatedly trying to start it.

Then I tried to jump start it and it just wouldnt start. I have tried to start it since but it just wouldnt. When I turn the ignition the car tries to start but it just seems to lack that final bit to turn over and start.

The recovery guy checked the spark plugs but they were ok. He disconnected some fuel pipe somewhere in the engine. He then turned the ignition but there was no fuel pressure.

The LPG side of the car was working perfectly before this happened and the car starts off on petrol so I doubt if anything in the LPG system is the cause of the problem.

I am wondering could it be the immobiliser? If so can someone explain to me how the car would behave once the immobiliser kicks in? How can i disable the immobiliser? Can you also give me some ideas as to what else could be causing the problem?

[kenney]

Hi A fault with the immobilizer, the engine will start and stop again after about 3-5 seconds,you can not disconnect the immobilizer,(although a good car thief probaly could do it).I would suggest put your ear to the top of the petrol tank and get someone to try and start the car listen for the fuel pump.have replaced lots of them.

[jasear]

Thanks for replying. Cant be the immobiliser then because they car doesnt start at all. Could be the fuel pump i suppose. What about thee relay? Do you know where it is located?

[kenney]

Yes it could be the relay but you have to find out first if the pump is working .The fuel pump relay is in postion 4 (208) on relay plate.

[billza1967]

Yes it could be the relay but you have to find out first if the pump is working .The fuel pump relay is in postion 4 (208) on relay plate.

hello mate if you go to this web page http;//www.go-lpg.co.uk/hints.html i think you might find some answers cheers bill

[jasear]

Thanks for that mate, it was very helpful. I think the following might apply to my situation:

 
8a. Always keep a 1/4 of a tank of Petrol in reserve. 

This will not only benefit you if you run out of LPG, it has far more serious benefits..... 
On most conversions the Petrol pump is still running whilst using LPG (for good reasons not discussed here). If the petrol pump runs dry whilst you are running the engine on LPG it can be burned right out. This is because the pump relies on Petrol to lubricate its bearings and keep it cool. Fuel 'slosh' when going round corners may leave a Petrol pump to run dry if there is only a gallon or so in your tank. 
The 'Fail Safe' Mechanism 
The most important factor to understand here is that if an unconverted car runs out of petrol the engine will stop. The car's management system will 'Fail Safe', turning off the petrol pump. This is an important protection device. 
If the car is converted and running on LPG things are quite different. The 'Fail Safe' mechanism has been defeated. The petrol pump will continue to run even if there is no petrol in the tank simply because the engine is still running on another fuel. This is why we recommend that all converted cars have 1/4 of a tank of petrol at all times, just to keep the petrol pump 'wet' and lubricated. Finally, make sure you use and replenish that 1/4 of a tank of Petrol in rotation - Petrol over 3 months old will have degraded to a greater or lesser degree and may not even be capable of running the engine at all! NOT what you want from a reserve fuel!

I had been driving the car on LPG the previous day on a long 120 mile round trip with little petrol (only realised when the next day the car wouldnt start on petrol). Well it did start but soon stopped. I think I might have killed the pump. Anyone know how hard is it to change the pump? Is it a DIY job that I can do myself? I know that the pump is located under the back seat.

[billza1967]

Thanks for that mate, it was very helpful. I think the following might apply to my situation:

 
8a. Always keep a 1/4 of a tank of Petrol in reserve. 
 
This will not only benefit you if you run out of LPG, it has far more serious benefits..... 
On most conversions the Petrol pump is still running whilst using LPG (for good reasons not discussed here). If the petrol pump runs dry whilst you are running the engine on LPG it can be burned right out. This is because the pump relies on Petrol to lubricate its bearings and keep it cool. Fuel 'slosh' when going round corners may leave a Petrol pump to run dry if there is only a gallon or so in your tank. 
The 'Fail Safe' Mechanism 
The most important factor to understand here is that if an unconverted car runs out of petrol the engine will stop. The car's management system will 'Fail Safe', turning off the petrol pump. This is an important protection device. 
If the car is converted and running on LPG things are quite different. The 'Fail Safe' mechanism has been defeated. The petrol pump will continue to run even if there is no petrol in the tank simply because the engine is still running on another fuel. This is why we recommend that all converted cars have 1/4 of a tank of petrol at all times, just to keep the petrol pump 'wet' and lubricated. Finally, make sure you use and replenish that 1/4 of a tank of Petrol in rotation - Petrol over 3 months old will have degraded to a greater or lesser degree and may not even be capable of running the engine at all! NOT what you want from a reserve fuel!

I had been driving the car on LPG the previous day on a long 120 mile round trip with little petrol (only realised when the next day the car wouldnt start on petrol). Well it did start but soon stopped. I think I might have killed the pump. Anyone know how hard is it to change the pump? Is it a DIY job that I can do myself? I know that the pump is located under the back seat.

im not sure about the pump mate but i think its accessed in the boot dont know how hard it is to change hope you get sorted bill

[jasear]

Can someone tell me how to change the fuel pump? Its under the back seat. I can take off the top cover which is fitted in with three scrrews. But I need to take the whole thing out.

Can you also recommend some company I can get the fuel pump from~?

[kenney]

Remove locking ring .Pull flange and seal out of opening in fuel tank. Unclip fuel gauge sender from reservoir housing and remove.Turn fuel delivery unit approx. 15° anti-clockwise onto stop and remove.You may have problems with the locking ring, these can be hard to loosen, if you have not the proper tool.