So far all I can figure out is that when the fuel returns at the sender unit it causes air to be stirred up and then sucked back up into the main line to the injector pump. Any ideas on how to resolve this? Paul Ottawa, Canada
Air bubbles have been in the return line since VW put that heat sensing valve in the filter. The bubbles are still on the current tdi's. I replaced the sensor with "o" rings and it slowed down a bit for a short while on my
99.5 jetta tdi. A few seem to be normal and fuel level in the tank seems to play into it also. Just replace the "o" rings, make sure the lines at the filter are good and the connections are tight. Then when you can't sleep count air bubbles instead of sheep!Joe
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