My guess: there's a leak in the fuel system which is letting in air, causing the fuel system to lose prime. Your car will purge air out but only after a lot of cranking.
Does the engine turn over? Does the glow plug light on the dashboard light up? If you're still on your original black relay 109, change it out for the new gray relay 109. They can fail and even if it's not the cause of the problem, it's suggested to change it out for the new gray style.
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