Mercruiser 502 magnum efi/mp gen VI
#6
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So if you gently pierce the power wire to one of the injectors that are not firing with a VOM meter or even just unhook it from injector and start it you will see immediately if it has power, no power then its just a matter of going backwards thru the harness. IF it does have power find the pin on the harness to ecu that grounds those 4 injectors and see if you have continuity at the j connector to ecu, I would do that before I started worrying about the ecu, would take you like 20 minutes with a 10$ elcectrical meter, fwiw
#8
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So take it a step further, see if the non firing injectors have 12 vdc, going from power supply pin on harness at injector to a good ground on motor, the 12vdc is present all the time when running/cranking, it might even be present when ign is just in run position, dont remeber for sure., the ground comes from ecu as it fires the injectors, once you determine which one is missing you will be able to narrow down the problem. The fact it doesnt flash tells us what we already know, that one of the two is missing, trying to help. IF you have 12 volts all the tim its cranking then we now the ground is missing, find what color the ground side of the injector pigtail is, find that same wire in j connector at ecu and test it with a ohmeter for a good circuit
Last edited by articfriends; 07-21-2015 at 01:49 PM.