does this fuel pump need a rebuild?

[Matt Andrews]

I have a 1966 912 with a 3 year old, 3000 mile rebuilt engine. I posted this in that forum but got no responses. I believe the fuel pump on this car is shared with early 911's so looking for a little guidance to troubleshoot. The fuel pump was done in the rebuild, which makes it a surprise that this went out, but would like a little feedback. Maybe it was a 30 yr old part sitting on the shelf that was used to rebuild this one.

Symptoms:
*When cranking the car, clearly no fuel getting to the engine. The clear plastic filter in the engine bay not filling with fuel.
*I disconnect the fuel line going to the tank and i can easily manually suck fuel to the pump. So no blockage in the tank.
*I pulled the fuel pump, and when you manually push in the piston, you get it to push air out the side going to the carbs. (If you cover the hole, the piston doesn't want to go down) But when you put your finger over the "source" side that pulls from the tank, it doesn't create any suction and the piston operates freely.
*all the gaskets under visual inspection look ok.

What am I missing? Just a rebuild kit?

Thanks,
Matt

[clarkd]

It sounds like you have a mechanical fuel pump. Here is my disclaimer: I don't own a 912, but have a bug with a mechanical fuel pump with a clear inline filter. The filter never has much level in it, but the carb gets all the fuel it needs.

You could buy an inexpensive electric pump from someplace like rock auto and test to see if you really have a delivery problem.