I've been chasing a fuel problem for a while now and appreciate any pointer from the community.

Problem - i only occasionally get fuel coming out of the injectors. Sometimes I get the prime, and sometimes not. Sometimes the jets will open while cranking, most times not. Occasionally the jets will spray when I turn the ignition off (I know - puzzling, right?). The engine runs when it gets fuel (so I have spark).

The battery tests at 12+ volts.
I get current at the connector to the fuel pump, and I can hear the pump run when I turn the key to "on" (but I don't get spray from the injectors most times).
You would think the fuses and fuel pump relay are good if the pump runs and the injectors occasionally spray.
I accessed the relay and reseated the connector thinking that might be the problem, no joy.
I've spent hours going over the test procedures and wiring diagram wondering what I am missing.

I've replaced the fuel filter.

Any thoughts? Is the relay "going" bad. What could cause the injectors to not operate if the pump and injector fuses are good (I can hear the pump run, and the injectors occasionally spray)? Is there a mechanism in the fuel Regulator/compensator system that will cause the injectors to not spray if the fuel pressure is low? What am I missing?

 

I had a similar problem...the harness that supplies power to the injectors had a broken wire INSIDE the insulation. The only way I found it was to wiggle all harness wires until the engine began to miss. The wire that went INTO one of the CONNECTORS was barely making contact at the break.
That might not be your problem, but moving/wiggling harnesses/connectors/relay/etc. might show if there is a broken wire.

 

Believe it or not, the "wiggle test" is something the manufacturers tell us mechanics to do! I've found a lot of faults that way.