Today I changed the fuel filter on this fuel injected Bug. I still hear noise coming from the gas tank when the fuel pump is running. Is there an extra screen inside the tank that might be clogged? It sounds like water is bubbling inside the gas tank or there might be an obstruction somewhere but I'm not sure. I cut open the old fuel filter but I didn't see it clogged up to the point where fuel couldn't pass. But for some reason putting on a new fuel filter helped quiet down the fuel pump and so now it vibrates less. How involved is cleaning this tank? Do I have to drive it until it is bone dry then take off the top part? How do you remove the screen inside the tank if there is one?
Also I would like to know about the torque ratings for the bolts that hold the oil sump in place. The 6 nuts underneath, how many inch pounds? Also the big oil drain plug, how many inch pounds should that be torqued at?
Lastly, the car makes a popcorn maker sound out of the exhaust pipe only when I am cruising down a long hill with the Bug in 3rd gear and no foot on the gas pedal or the clutch. It does not do this 100% of the time. Probably about 85% of the time it will do this. Depends on the incline and how fast I am going.
The decelerator valve works great so it's not that. My valves are adjusted at .006 so it's not a tight valve. My ignition timing and dwell is set correctly. And I just can't figure out what would cause this. The Auxiliary air valve and 5th fuel injector also seem to be working fine.
If the Bug has a faulty air box/air flow meter. What would be the signs and symptoms?