Well she started up perfectly this morning, so that was a good start to the day, and suggested that the pump and injestor seals etc were more than likely fine.
The handy thing about having the clear pipes was being able to see exactly where air was and what it was doing in the return and feed lines.
So next step we went back to standard setup but with a clear loop in the feed to the pump.
The car struggled to start like this, and lots of air bubbles could be seen entering the pump, definitely not good. So we knew the sender wasn't the problem so most likely culprit as always, the filter unit. We decided we had to take out the housing to see what was going on, this turned out to be an epic task. The screw holding the filter housing into it's metal bracket was seized, so we had to drill that out, then it would still not shift at all. The housing was totally rusted onto the frame that it should normally slide out of. So then we tried to remove the frame and filter together. One Torx bolt and 10mm bolt were accessible, but a third was hidden up behind the filter housing, not even visible. Of course normally this would be accessible with the filter housing dropped down, but not possible for us. We managed to get a 10mm spanner onto it and get it moving though, and it was a painfully slow progress. Me and Richy took it in turns to work on it, and I think it took about 3 hours to get the pesky little bolt out, but finally it came, and the housing with it.
Even with the whole thing removed we could still not seperaqte the frame and housing at all, and were very concerned about damaging the no longer available filter housing. I had to grind off part fo the frame before we could seperate the two.
This is the frame, which needs welding up, and also that bolt taking out, and a good clean up of course!
The filter housing looked okay, so we rigged it up to vacuum test it, and it held a vacuum okay. So the housing itself didn't seem to be the issue, so most likely the connectors to the housing were the problem.
We found some bits of pipe to enable us to bypass the filter housing altogether, to see if that solved the problem
Like this the car started and ran fine with no air at all in the feed, so we had finally found our problem, but not exactly which connector was causing the issue.
We had to leave things there, but I plan to sort out the filter housing and frame so it is all functional and trouble free, then cut off all the troublesome connectors and use hose and nice quality hose clamps. Richy thinks it would be better to leave the returns connected together bypassing the filter, as it seems a strange setup and causes problems, so I will ponder that. He has never seen another fuel system that is like this, with the return into the filter and the fuel cooler etc, so I'm wondering if anyone else has cars with fuel coolers on?
It's been a very tortuous process indeed, but hopefully I am homing in on a good result. And if you haven't got the shield fitted over the fuel filter on your car, then I would try and sort something, because mine has suffered badly from not having for who knows how many years?