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Hi Dave,
I know you're trying to help here, but based on your contributions below I believe you misunderstand the CPS and its role with FI and Ignition.
"crank position sensor tells fuel computer which is located in passenger side kick panel, to turn on fuel pump relay.. i do not think it stops the spark. it just stops fuel pumps if no crank motion is detected."
The CPS has no direct contact with the FI system at all. Its timing pulses go only to the Ignition CU, which passes them on to The FI ECU to allow FI operation and time the injectors. For safety reasons, as in an accident, no ignition means no fuel.
"if your prob really is the hall sensor in the distributor, "
• If the car has a CPS ('89 on), it won't have a hall sensor.
"please do a test, pull the crank sensor plug and note, you should still have spark but it won't start. good to know for future troubles someday."
• As described above, there will be no spark with the CPS disconnected. The start-run sequence below has more details:
Start-Run Sequence (240 '89 and up)
1) During starter cranking, the Crank Position Sensor sends timing pulses to Ignition Control Unit
2-a) The ICU uses these CPS pulses to trigger the Power Stage (aka Ignition Amplifier), which initiates spark from the coil.
2-b) At the same time, The ICU also propagates the pulses to the FI ECU, to allow FI operation (no ICU pulses means no FI operation).
3-a) The Fuel Injection (System)* relay (previously energized at Key On) powers the AMM, IAC, ECU, Injectors, and Fuel (pump) relay coil + side.
* The System relay is in the white case with the Fuel relay.
3-b) When ICU pulses are received by the FI ECU, it "energizes" the Fuel relay by grounding the relay coil (– side) to run the fuel pumps.
When all these things work, the engine runs until the Ignition is switched off, which in turn shuts down the FI system.
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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