matt_moore
Member
This has been a recurring intermittent problem that has been progressively getting worse (happening more often). I've had a pair of mechanics look at it and neither of them have been able to properly diagnose it as of yet. As the title states, the engine will periodically stop firing in cylinder 5/6 (bottom two). The issue appears to my non-marine mechanic brain, to be fuel related, like the injectors are not firing. How I've come to that conclusion is by spark testing the cylinders when the engine is not running on 6. Pulling each spark plug wire one at a time I've been able to determine all six cylinders are seeing spark. I recently had all the injectors cleaned, with the screens replaced. I also had the VST cleaned. We did a fuel pressure test and have 35 PSI at the schrader valve. I've eliminated the fuel tank by running the engine on a portable as well. Does this early version of EFI have a limp mode? Could the ECU be seeing a parameter it doesn't like and shut those injectors off to protect the engine (seems unlikely because then you have cylinders running without lubrication). Is the only thing that has influence on the injectors firing or not the ECU or does the yellow lead trace elsewhere (ie. switchboxes, voltage regulators, trigger, etc.) I haven't been able to locate a wiring schematic. Would also be helpful to know if there's a place I can bring my ECU to for diag, ideally local to NH. Thanks in advance for any help you can provide.
