1997 Sonoma with 4.3l. Do not have any power at ecm #9 fuse. No power at fuel pump.

zq8sonomazq8sonoma Member Posts: 1
edited January 2016 in GMC
Changed fuel pump and truck ran. Fuel pump retaining ring came loose because of rusted tank. Replaced tank now truck will not start. No power at pump, ran ground wire to make sure there was a good ground.
No power to #9 ECM fuse. Can not locate oil pressure sending unit. 1 book showed the unit behind manifold but I do not see it. Any possible ideas where this is located or other possible ideas


  • chevyguy14chevyguy14 Member Posts: 2
    with the pump, you may have shorted out the ECM. You could check to make sure that there is not a relay burnt out. The oil pressure unit should be behind the driverside manifold.

    look here:

  • thecardoc3thecardoc3 Member Posts: 5,435
    edited February 2016
    If you have no power to the ECM #9 fuse, why are you looking for the oil pressure sender? It would be one thing if the fuse was failing and causing no power to the pump relay and the PCM, but you wrote you have no power to that fuse. If you really don't have power to fuse #9, check and tell us if the parking lights work or not. Fuse #9 and the parking lights both get power from the same 16ga fusible link wire at the junction block. The easiest way to check fusible link wires is to just grab hold and pull on them one at a time. A failed one will be broken inside the insulation and tear apart with very little effort.
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaMember Posts: 64,482
    Doesn't his truck have a fuel shutoff function wired to the oil pressure switch?
  • thecardoc3thecardoc3 Member Posts: 5,435
    The oil switch is an alternate path to power the fuel pump, should the relay or its control circuit happen to fail. Crank the engine until you get oil pressure, and that turns the pump on. I have had some switches that failed internally and would switch the pump circuit to ground blowing the fuse, but the OP states there is no power to the fuse, not that it is blown.
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