Help I need some advice with a 72S MFI problem.
The car has been put on a dyno and it has been concluded that there is a problem with the injection pump. Basically at lo and high rev's the CO levels are ok but in the mid range ~3000rpm it leans right out but the graph is all over the place. The problem has come up fairly suddenly (over a couple of hundred miles but over several months ) so I hope and don't believe that it is a wear problem. About 2000miles ago I had the car on the same dyno and the CO graph seemed fine at the time and the car has been fine until this problem. I have changed the fuel filter and had the fuel pump checked. We have richened the pump right up but it is still lean in the middle. I have been through the links here and found quite a lot of info on MFI's but nothing specific to my problem so if anyone could help I would appreciate it.
Another question I should ask is about having the pump rebuilt. I am in Australia and one of Pelican's articles mention Walz diesel injection (in australia) as one of the rebuilders of these things. Has anyone direct experience using them?, I have not got positive feedback locally about them and have heard that the recommended coarse of action here is to send the pump to the States to Pacific Fuel Injection. Can anyone give me an idea how much it cost's to do this?.

Thanks
Shane