jetboating
New member
I have a 2009 Marine Power 385hp 8.1L (330 hours) and I was hoping to get some advice or guidance for a technical issue I am experiencing.
I have a video of the problem here: https://youtu.be/ho53LJPfhqs
Under load, primarily in reverse, the engine is surging/pulsing from 2500 rpm down to 1500rpm. It doesn't do it as much in forward. I think it's doing it in reverse because the throttle lever has a much shorter throw in reverse than forward, thus applying throttle faster.
I've checked:
- rail pressure (44 PSI at key cycle)
- 38-40 PSI at idle.
- 38-39 PSI at 3500 rpm.
- pulled off vacuum hose while running, fuel rail pressure jumps up about 6-7 PSI.
- checked all spark plugs. They are sooty, dry black indicating a rich condition or weak spark, consistent across all 8 cylinders.
- made a makeshift smoke machine and blew smoke into throttle body, no visible vacuum leaks.
Thank you for any help or advice?
I have a video of the problem here: https://youtu.be/ho53LJPfhqs
Under load, primarily in reverse, the engine is surging/pulsing from 2500 rpm down to 1500rpm. It doesn't do it as much in forward. I think it's doing it in reverse because the throttle lever has a much shorter throw in reverse than forward, thus applying throttle faster.
I've checked:
- rail pressure (44 PSI at key cycle)
- 38-40 PSI at idle.
- 38-39 PSI at 3500 rpm.
- pulled off vacuum hose while running, fuel rail pressure jumps up about 6-7 PSI.
- checked all spark plugs. They are sooty, dry black indicating a rich condition or weak spark, consistent across all 8 cylinders.
- made a makeshift smoke machine and blew smoke into throttle body, no visible vacuum leaks.
Thank you for any help or advice?