Yes, remove that line and check that it isn't blocked up. Check all the way from the injection pump, to the protection solenoid, to the intake. Also look for leaky hoses or connections.

-Jason

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1991 350SDL. 230,000 miles (new motor @ 150,000).

Tesla Model 3. 136,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.