Hello again gents.

I gave my old 59,000 mile 03 SDI to my son, and it has served him well. He came up home for a funeral and had it serviced at the local small garage while he was here. After the service, which involved a fuel filter change, it was very stubborn about starting and blew out a cloud of white smoke from the exhaust when it did get going. Once it has run a few minutes, all is fine, and starting is easy as it always has been.

He has now returned to London with it, but I am concerned that it will continue like this. The only ever time it did this was after I had the cam belt changed and the fault was traced to having had the fuel supply line broken into during the dismantling. The mechanic took it back that time (main dealer job that time) and fixed it. I don't know what he did, but he said it was a fuel pump, 'resting pressure' issue.

Can any one shed light on this problem?

I feel that the smoke and smell it made on starting, shows fuel was pumped into the injectors and cylinders,but not combusted. Therefore, I am puzzled about how the fact that the fuel line was opened yesterday could create this problem. It had done a few miles between the service and the problem showing, but only about five.

Puzzled.......

Edited 25 January, 201115 yr by EvilV

He had the fuel filter replaced again, and the problem has gone. I still don't understand why this would happen though. Any ideas?

He had the fuel filter replaced again, and the problem has gone. I still don't understand why this would happen though. Any ideas?

Perhaps the filter was filled with fuel this time. If the filter is not filled when fitting it can be virtually impossible to start.

Perhaps the filter was filled with fuel this time. If the filter is not filled when fitting it can be virtually impossible to start.

Thanks Peter. Yes I can see that, but what puzzles me is that after a lot of trying, it did start in a cloud of smoke, and once she was warm, she started easily enough. Next morning, though, it was the same again. Are you saying that if there is a void of fuel in the filter, the car will run normally once going, but will cause problems again next morning?

These two occasions where this problem has come up, are the only times it has ever given the slightest problem. It has beena very reliable car altogether, and incredibly economical to run.

Regards

Tony

Edited 26 January, 201115 yr by EvilV

Bad connection/joints will allow air into the fuel system overnight. This will cause problems as the injectors can't push in air to any useful effect. Once there is enough fuel to fire properly the left over fuel from 'failed' revolutions will burn away giving smoke until the cylinders are burning fuel properly. Sounds as though you have fixed the problem with a new filter. If it recurs check clips and pipes. Hopefully you'll never have need to do so.

Did the mechanic replace the O rings on the fittings that go into the filter?

If not, air may be getting into the system. Genuine VAG filters come with replacement O rings in the box.

Thanks for the ideas. It makes much more sense now when I think about the air leak idea.

Cheers

Tony