Q: Car cranks over but won't start - 2004 Nissan Sentra

asked by on October 21, 2016

Put an obd2 chip in a while back which leads to believe its the computer ecm, no coils are getting spark, all fuses and relays are good, just replaced fuel sending unit, but cant hear the pump kick on when turning the key.

My car has 182000 miles.
My car has an automatic transmission.

If the fuel pump is not "whirring" momentarily when you turn the key "on", either the pump is not receiving power or it’s non-functional. You might try probing the fuel pump harness for 12 volts at moment key is turned "on". If you do find that there is no power being supplied to the pump and there is also no power to the ignition system that would seem to suggest a "global" fault, in the ECM for instance, but the ECM is only one possibility (there are also relays involved).

The ECM has a self diagnostic which potentially could have set a DTC (Diagnostic Trouble Code) and so you should use a code scanner to see if such outputs exist (or were set). You might also try removing the chip you added and then "re-setting" the computer by disconnecting the battery negative terminal for 5-10 minutes.

If simple tests such as that just described do not work out for you, by all means contact YourMechanic and a mobile expert will be dispatched to diagnose this no start condition for you.

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