1 why 11volts? check your battery volt, it should be 12.5+V. either that or you have, like a lot of us, a cheap-o multimeter. not uncommon. but 2 you have fuel flow, so thats a good sign. why are you having problems with the 1 injection pipe? by the way its the injector pipes here, to/before injectors. one thing you can do, hook up a bottle of diesel purge, run hoses accordingly. which would be find a connector, it should be a 3/8 OD, can probably find at like a plumbing shop, run fuel line extension to bottle, disconnect fuel return from pump, tank another length for fuel line, run to bottle, prob also need the extra clamps for this. with inj pipes either disconnected @injectors, or take off pipes altogether, will make a mess squirting out of pump, or with out pipes connected properly, you can take some cloth to protect rad hoses, and battery and such. now crank motor, and get purge thru and see if you can get fuel flow thru all 4 pipes/or squirters.
one smart thing to do here, so you dont have to stop and let starter cool down, you can remove glow plugs, you now should be able to just crank(freewheel) motor and not have to stop, do make sure to check starter that it doesnt overheat. its also possible to take injectors out, however you have to do it right, and if you dont have a lot of experience here, i dont want you to ruin your head by not knowing the correct way how. youd also need new heatshields for removing injectors.