replaced 2nd filter, still no run. Don't see any way to open up the filters from the top. Injection pump is a Bosch 30-2. On top of Bosch there is a square metal piece that looks like it holds a diaphragm. Middle of that piece has what looks like a button or a cap. Cap is loose but will not lift out of the rim it sits in. Front of pump has a cable that looks like a shut-off cable with a thumb lever. Cable stays forward when running or shut off. Only way to bleed it that I see is loosen the injectors at the engine but I expect there would be something built into the system that would bleed it. Thanks for previous answers.