Congratulations! Fitting suction to the return line and cranking IS bleeding the air out of the injectors. It would have started quicker if you had maintained the suction (second person) whilst cranking.This afternoon I reconnected the inlet pipes to the tandem pump, and hooked up my vacuum pump to the return side, and pumped away. I got loads of air through, and some fuel. I couldn't get a clean flow of fuel without air. I had the battery charged up so I thought I would give it a go anyway, not expecting it to start, yet it sounded like it might, so I kept cranking, and away she went after about 20 seconds cranking. This was a big relief because I wasn't wanting to have to bleed the injectors!
So I returned all the piping back to normal and she started right up again, so I went for a little drive and she drove fine. When I got back I waited for a bit and then tried her again and she didn't want to start. I realised I still hadn't really resolved whether there is air in the system or not, so I put a short piece of clear pipe back in the return line and started her up again, it took a lot of cranking to start her but she fired up. I was surprised at how much pressure was in the return line, and in the clear pipe was a white froth, my connections were also leaking so I shut it down pretty quickly, but it would certainly seem like there is an air leak somewhere.
I need to get a better connection piece and some better hose clamps if I try this again, but really I need to start the hunt for the air leak, I iwll start looking around the fuel filter housing as the most likely culprit.
So I guess some kind of dubious progress has been made..
Let the great debate about the mysterious black stuff continue. What is it, and where does it come from? Can these questions be answered, we will have to wait and see
The Froth coming down the return line in the clear tube is exactly what I would expect if you are getting air in the feed line. this is the air that is bled out of the injectors
So you have found the cause of the poor/non starting. My hat lives to fight another day (ref my post#88)!
Next thing I would try is to rule out everything except the tandem pump or it's gasket. To do this I would use a new fuel pipe connected to the tandem pump fuel in and feed it fuel from a bucket/jar. Get it started by sucking on the return again. Run it for a few minutes to allow all the air out. Stop it for a few minutes and try restart. Make sure the feed tube is always in the diesel in the bucket and doesn't pop out else youll have to start all over again. If it still fails to start well the the answer is the tandem pump or gasket. If it starts well the "air in" leak is further up the feed line.