Fuel Pump Questions, Was: FI Wiring Question Options

[ThinAir]

It looks like I've got a bad pump. Everything is plumbed to match Dave Darling's hose diagram and I've checked it against a known good 73. To be sure, I did some additional testing.

The connector that is closest to the electrical hookup is the one that has the T on it to connect to the return line in the tunnel and to the fuel pressure regulator. I'm testing by hooking the gauge directly to the center outlet of the pump.

If I clamp between the T and the fuel pressure regulator, I get about 1 psi on the gauge. If I clamp between the T and the tube in the tunnel, I get about 10 psi.

If I test with no lines clamped, I get about 5 psi.

I bought this pump a few months back and have never used it until now. The Haynes manual says that the pre-72 and 72-74 pumps are "similar". I don't know for sure what year this one came out of. Does anyone know if there are any differences between pumps? Like, should the two "outside" hose connections be reversed?

Does any of this information give anyone a clue about what is going on?

[Dave_Darling]

The stock pumps (70-74) have small labels next to the fittings. "S", "D", and "R".

S stands for Suction (or rather, the German equivalent which also starts with S).
D stands for Druck, which is German for Pressure.
R stands for the German word for Return.

So you hook up the larger center tunnel line to the fuel filter and then to the S port.
You hook up the D port to the right-side fuel rail.
You hook up the R port to the "Y" fitting that connects to the Fuel Pressure Regulator and also to the smaller center tunnel line going back to the fuel tank.

Any pump should be fine--as long as it puts out enough pressure and volume. Pumps that do not have an "R" port are fine, just remove the "Y" fitting and plumb the FPR directly to the smaller center tunnel line.

--DD