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"I replaced the relay with a good one and jumpered the pumps to check. Both work."
If by "work" you mean the Fuel relay clicks twice when you turn the Key on—that's not enough. To be fully working, the relay has to click again when cranking. This is the sequence (after that first double-click):
1) Engine cranks and CPS pulses go to Ignition CU
2) Ignition CU initiates spark AND sends pulses to FI ECU
3) FI ECU energizes Fuel relay to start FI operation
"If a fuel pump wasn't working would it send a signal to not spark? I'm assuming that the no-spark condition is the specific problem, not something caused by, say, a fuel issue."
As the sequence above shows, the ICU "allows" Fuel operation by sending pulses to FI, signifying it's working (as far as it knows). In other words, "spark trumps fuel".
• You say the plugs are dry? Meaning after the no-spark cranking there is no sign of fuel on the plugs?
If so, that's normal for an Ignition-based problem (No #2 above means no #3 either).
• Jbowser's tip on Fuse #6 is worth checking too. It may be passing enough current for the Key-On relay click (and brief pump run?) but not enough for full Ignition + FI operation.
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Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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