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Discussion Starter #1
I have a 2004 Passat TDI. My son has been driving it and now it won't crank, I've replaced the fuel filter but when I turn the key on no fuel comes out of the supply line. I hear a little noise at the pump but just for about 2 or 3 seconds. The only fuel that came out came was from the "out" line off of the fuel filter and it was black, almost like it had dissolved something made of black rubber, another description is, it looked "sooty." Shouldn't I have enough pressure (with the fuel supply line feeding into a cup) to fill a plastic cup within a few seconds when I turn the key to the "on" position? Because I get nothing, zero, zilch, nada. Any advice would be helpful, thanks.
 

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Also remove the line at the fuel filter and try blowing it out with compressed air. Black in the fuel is either contamination or stuff like algae growing in the tank. if you blow it out and it's still no go the pump is bad. If you blow it out and more black stuff comes out, dump some biocide for diesel fuel in the fuel tank and change the fuel filter after the tank is done. Fuel should squirt out when you turn the key on.
 

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Discussion Starter #4
I tried removing the pump. There is one 4 wire connector and 2 other connectors with either wires or tubing about 2 inches apart. How do I remove them? Are there special tools involved? I also read that this is a low pressure supply pump (6-8 lbs.) and it basically just opperates from suction supplied by the injectors, therefore necessitating a system with zero leaks (indicated by bubbles) to operate. Am I understanding correctly? And as you mentioned, fuel should still squirt out when the key is on, since mine doesn't squirt, wouldn't that be the pump?
 

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Are you saying that you hear the fuel pump buzzing for 2-3 seconds and then it stops with the car on but engine not running or with the car on and engine running? Did you remove the fuel line without the T or the fuel line with the T? The one with the T is the return lin. The one without the T is from the fuel tank.

Ruling out any clog in the filter or fuel lines, it sounds like you have a bad pump to me. The 4 wire connector should unclip. The 2 fuel lines have internal clips. Use a thin screwdriver to press the notched in area in while pushing the fuel line down towards the pump. This should release the clip and let you pull it off. All PDs are the same in that the electric fuel pump pushes fuel and the tandem pump pulls and pushes fuel to the injectors. If the electric fuel pump dies you need zero leaks to work or else air will get pulled in by the tandem pump. If you take the pump out make sure to have a plastic tarp under it or else your interior will stink like diesel.
 
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