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Yes, it's a good idea to replace the crank sensor at that age anyway.
But I'm not sure you verified "cranking" fuel operation — as opposed to the short pump "buzz" with the key just "ON" in position II. It's not clear when you say:
"No then, the fuel relay switches relay activation when cranking, while the key is in ON one relay activates (fuel pump prime I guess) then shuts off and activate the other. When I crank it(?) activate again, but no spark."
Not sure what the underlined "it" refers to, since we have two relays to consider. Here's how those two FI relays should work, relative to Key operation:
• KEY ON (II) — The SYSTEM (or Main) relay closes immediately to apply voltage throughout the FI system. And the ECU "programs" a short closing of the FUEL relay for the so-called "prime". (Note that this is NOT the normal Fuel relay control needed for start/run.)
• KEY CRANKING (III) — The SYSTEM stays closed. And the FUEL relay closes again to run the pumps — but ONLY if the FI ECU has received timing pulses from The Ignition CU.
With the white cover off, watch and confirm these operations:
1) Key to II — The System relay closes (and stays closed), the Fuel relay closes then opens after 1 or 2 seconds.
2) Key to III — System relay still closed, engine cranks and Fuel relay closes as long as cranking continues.
Let us know if you are getting the Fuel relay closed in condition #2. I'm assuming you are, although you didn't answer my question about "wet plugs" in my Tuesday response above.
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Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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