When re-installing my delivery valves I put a very small amount of white lithium grease on the crush washers and end of the spring to hold them in place while I re-installed them. It's not something I read about specifically relating to this job but often find that when you need to provide just a little hold the grease works well and as soon as the fuel starts going through I am sure it disolves and got pushed through the injectors.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz