[Roadsters] Z carb help

[Tim]

Hi all. 

We have another new member to the Dairyland Datsun Club who has asked for some help with his carbs. He has a 70 240 and is in the MKE area. This is what he sent me so far: 

"The problem is with the slow speed circuit on the rear carb.  It will run at high speed, but appears to not provide fuel to the rear three cylinders at slow speed.  I checked this by pulling plug wires at idle and found no difference at idle for any of the rear three cylinders, as opposed to the front cylinders fed by the front carb.  I'm somewhat intimidated by SUs, as I've never worked on them.  What I've read tells me there is some kind of hydraulic dampening in the carb, and I hesitate to start tearing it apart.  I have a repair manual for the 240Z, but am still not sure what the issue may be.  If you or other members have any suggestions, I'd appreciate some guidance."

Dan has suggested a few things that can be checked without major surgery but I thought I would post this for Don and see if anyone out there can help. 

TIA

Tim
Dairyland Datsuns