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how many cranks before it starts?


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IIRC from reading the Renix manual there are two "modes of operation" that proceed in sequence: "Key on" mode and then "crank" mode. During the key on mode, the fuel pump relay is energized and the ECU completes the circuit for up to three seconds to prime and build up pressure in the fuel log. Then, once crank mode is engaged, the ECU determines if proper cranking speed is achieved, and "learns" the location of cylinder 1 or 6 to begin the firing order and the injector sequence.

 

One consequence is that if you turn the key from "off" straight to the start position, it may actually take a bit longer to start because you rushed the priming of the fuel log, and might have a lean F/A mixture for the first few ignition signals.

 

I just finished reading the manual last week, so I hope I retained that info correctly. :smart:

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My MJ takes 4-8 turns to start, always has. The 97+ XJ's (have three of them in the family) used to always start on the first 2 cranks, but now two of them have fuel pumps that do not prime to operating PSI at key on and they take 10-20 cranks to start if the pressure on the fuel rail has depleted. If they were mine (these ones are my parents) I would have replaced the pump, but they have been running it on the old fuel pump now for about 3 years on one of them and 1 on the other with no other problems.

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