BMW Bavaria + Carter 4070 Fuel Pump

When I was unable to successfully rebuild the OE Zenith carburetors on our BMW Bavaria (no patience), I bought a pair of used Weber 32/36 DGAV carburetors (with the linkage and a manifold) on eBay for $99. I bought rebuild kits and some new jets from Pierce Manifolds (because they’re sort of close to me).

Carter 4070 Fuel Pump Mounted on Firewall

For some reason, I also decided to replace the mechanical push rod driven fuel pump with an electric rotary vane pump.

I found that Top End Performance had a discourse on the Carter 4070 fuel pump saying it was a good pump for Weber carbs. I first mounted the fuel pump on the firewall, near the overflow tank.

On the highway, I noticed that the car would occasionally stutter and I realized that the engine was becoming fuel starved because the pump was designed to be more of a pusher, closer to the gas tank.

I moved the fuel pump to underneath the car, just forward of the fuel tank. I used a Napa 1814U “Quiet Pack” that mounts the pump on rubber bushings to isolate it from the car’s frame and ran the 12v+ for the pump from the fuse box.

Carter 4070 Fuel Pump (Note: wiring polarity is incorrect in this photo – it is reversed)

I also bought this Holley shut off switch that works off of engine oil pressure. Joe Weir, on the Senior Six Registry mailing list sent me a diagram that uses a relay (12 63 1 276 165) from a 320i for fuel shutoff.

The only problem I’ve had is with the electrical connections to the pump falling off – they’re held on by friction. To resolve this, I put a dollop of JB Weld on each terminal, then stuck the connectors on.

Carter fuel pump installation notes, pages 3-6 (PDF)