1982 Volkswagen Vanagon diesel 1.6L NA

I just installed a rebuilt fuel injection pump and drove approx 3 miles and the pump is leaking. It doesn’t appear to be coming from the mail shaft seal, the unions or the valve stem. Cannot detect leak at idle. I replaced fuel, fuel filter, and fuel line from filter to pump prior to starting. If the injectors are partially blocked could this cause the problem? Am looking to replace injector tomorrow.