Here`s a shot of the new pump when arrived. It`s a genuine pump with low miles, identical to the pump I had in the car before, and the label says it`s for the 987... It fits perfectly though. It also looks better built than the original 986, it`s a more sophisticated design: here the pump is sitting in a separate housing and suspended on rubber dampeners. If you scroll back, you can see the rubber suspension in a previous post.
I wanted to see the condition of the pump that I replaced. It`s not servicable, because the aluminum casing is crimped on the motor, so I had to peel that off destroying the pump housing. Doesn`t matter because the output port was broken off anyway.
Here`s the rotor with the actual pump unit. It`s basically two pumps on the same shaft: a low pressure pump and a high pressure pump. If I understand correctly the low pressure plastic pump is there for filling the pump chamber with fuel. This probably helps maintain a steady pressure regardless of the fuel level in the tank, also keeps gas around the motor all the time for cooling, even when the level in the tank is very low.
The high pressure pump is a trochoid pump with steel rotors spinning in between ceramic plates. This pumps gas upwards through the electric motor all the way to the injectors and from there back to the tank.
Everything looks pretty good, except for the commutator being pretty worn down.
Interestingly the carbon brushes look barely worn.
If you ever wondered what`s in the top section of your fuel level sending unit, here`s the answer: a big steel ball. I assume the function of this is that it closes the breather line in case the car is upside down to prevent gas spilling all over the car. Good to know i don`t have to rush out from the car next time when i flip it over... If you have a better explanation for the role of this let me know.
I had to rewire the sending unit because the old gas stripped the wires almost completely.
Long story short, the engine runs now with the new pump. The car is still jacked up on the driveway, I need to change all the fluids and I need to buy four new tires because the old ones all got oval.