Phil P Posted May 27, 2002 Share Posted May 27, 2002 Hi all, The twin 40s on my xflow seem to be emitting small amounts of a brown oil like substance. It seems to be coming from the vent above the left air trumpet on each carb. I'm running a pipercross air filter & backplate and after a good run the interior of the backplate is finely covered in it and it seems to collect at the bottom of the backplate and on the underside of the carbs. The liquid is a fairly dark brown/ caramel colour. Does anyone have any ideas as to what this is and why it is being produced - Anyone else seen this, is it normal weber behaviour? Many thanks for your help Phil Link to comment Share on other sites More sharing options...
Peter Carmichael Posted May 27, 2002 Share Posted May 27, 2002 This will be fuel. A certain amount of fuel vapour always hangs around the filters when you run the engine just off-cam in a phenomenon called "stand off". Anything more than a light condensation could need looking at. Link to comment Share on other sites More sharing options...
Phil P Posted May 28, 2002 Author Share Posted May 28, 2002 Thanks for your comments Peter Still puzzles me stightly as to why the liquid should be brown in colour, I would have expected fuel vapour to be relatively colourless, as with petrol. As it arises from when the engine is off cam, it looks like I haven't been driving fast enough! Phil Link to comment Share on other sites More sharing options...
acbateman Posted May 28, 2002 Share Posted May 28, 2002 This could be the float heights - if they're wrong the carbs can overflow and the resultant petrol and oil filter oil mixture drips out. Link to comment Share on other sites More sharing options...
stevefoster Posted May 28, 2002 Share Posted May 28, 2002 You have a slight leak and the evaporated vapour mixing with all the other oil vapour around an XF is producing the brown stuff. If it is not very much I would not worry about it. You can try tightening the 4 screws under each carb or even replace those gaskets. Other causes could be fuel pump pressure overcoming the float valves = new valves or fuel pressure regulator needed esp if you have an electric fuel pump. Link to comment Share on other sites More sharing options...
Swiss_Tony Posted May 28, 2002 Share Posted May 28, 2002 My vx does this a lot! I normally have quite a few streaks down the side of the car after a blast. If you have a bit of a silly cam it will be a lot worse. The first time I saw it happen on the dyno I was amazed. James Link to comment Share on other sites More sharing options...
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