A few weeks ago, I removed my car's transfer pump screen, cleaned it, and put it back into the tank.
As it turns out, the fell out when I put it back into the tank. The pump sucked all the rusty gook out of the tank and sent it into the fuel system. A few weeks later, my car started running on two cylinders.
A flow test of the injectors led me to discover that the injector's pickup screens were clogged with crap.
obviously, most Scirocco fuel injectors do not look like this, but CIS injectors are the same, they also have a screen in them. Note the clog.
So I removed the fuel filter. That bucket was white. All of the black stuff came out of the filter.
I cut it open, and saw bad things:
Time to flush the fuel system. First, I wanted to flush the feed side to clean all of the pumps. I put in a clear plastic 5/16" carburator fuel filter, and ran the hose back into the fuel tank. I ran the pump for more than an hour like this.
Here's the crap I collected:
Then I put a new fuel injection fuel filter in (not clear) and hooked the fuel rail back up. I pressurized the fuel system, and let that run for another hour. You can't use a clear plastic filter for this because the fuel pressure regulator runs the system at 43psi, more than the max 8psi of the fuel filter.
I soaked the fuel injectors in a tray full of SeaFoam overnight.
All is well now!
Moral of the story: CHANGE YOUR FUEL FILTERS!