#1 sleeve set and #5 sleeve set aren't connected except by the camshaft, so I have no idea why you get more fuel when #5 is open.

Sounds like your #1 plunger spring is broken, so the plunger stays up instead of re-filling with fuel for the next injection. Not an expensive fix, but the pump does have to come apart!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!