I have a M4500DT. I have been replacing rings etc in the engine, so I havent put the front on yet. Radiator not on yet or power steering etc. Its just the block on the tractor. I decided to compression test it before complete assembly. Also I have connected the injector pump and lines to the injectors to be sure no contamination before putting everything back. I bled the fuel supply to the injector pump and 5 delivery valves are working, but number 1 doesnt work. This is only on battery crank, with a very good battery. I thought I had not lined the pump rail in the speed control fork. It wasnt that. The governor springs are on properly. I have taken the IP off a number of times to try different things. During one crank #1 did work a little bit then stopped again. Number 2 doesnt work sometimes during a crank. I notice that #2 has some bubbles with it sometimes so was wondering if its still air in the IP.? But why are 4 working well and most of the time 5 are, surely the fuel is there? There are 4 shims. I tried taking them off to see the difference(not concerned about timing at the moment). It seemed the delivery valves were weaker pumping, I wouldn't have thought there would be any difference as far as my limited knowledge goes shims are only to do with timing. I have a new fuel pump (after market) it seems to be pumping okay but I also tried a direct gravity feed from the shed roof with a bottle of diesel and a long fuel line. Still the same. I was wondering if I ran the engine starting on 4 pr 5 cylinders then at speed would the #1 delivery valve prime itself or should it be working on battery crank? There was nothing wrong with the pump before I stripped the engine. I bagged it in a plastic bag until the rebuild. The manual says dont mess with the pump. One thing I see I havent done is smear the shims with three bond 1215 or equivalent. I have Hylomar Blue. Its a bit messy and it would be hard to smear a smooth thin coat unless it can be thinned. I will try this next but open to suggestions please?