Had another play around this morning. Couldn't find any restrictor in the return line. I went back to stock wiring, same lean result. I then grounded the pump -ve to take out the fpcm circuit and back to extremely rich again. At this point I'm thinking about putting the walbro back in, checking AFR again and seeing if the wiring changes have the same effect.
If the same thing happens I'm thinking possibly the fpcm is stuck in low voltage mode and was tuned like that. Thoughts please.
Moving forward, to correct the rich conditions with direct power, retuning will be required. Correct?