You haven’t mentioned what the pop-off is set to. The minimum cylinder pressure should be 160 psi. To check, pull the plug, screw in the tester, disconnect the TCI, shut the fuel off and spin the motor up. Try a couple of times to verify the result.
What is the condition of the pulse line? It should have a fit tightly at both ends, show no signs of cracking, not kinked and be pliable. Is there a tightly installed tie-wrap of safety at both ends?