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  1. K

    Mercruiser 350 MAG MPI missing only at 3000 rpms

    Here are some different photos of same plug. The porcelain insulator is definitely clean. If agree I have heavy carbon/oil looking deposits on inside and outer.
  2. K

    Mercruiser 350 MAG MPI missing only at 3000 rpms

    If guage is correct, it is 175. Which does seem a bit high as I believe I read it should be 160? Only been about 8 hours of use since oil change, so hard to say on consumption, but still has same level of oil on dip stick. trying to get a Mercruiser VesselView to work to look at my RPMs and...
  3. K

    Mercruiser 350 MAG MPI missing only at 3000 rpms

    N No fuel additives that I know of. Boat probably had 55 gallons of fuel when I bought it. Not sure of fuel type or age of fuel. I topped it off with non ethanol 87 being 28 gallons about 8 hours of use ago. Im going to track fuel usage a bit closer, but fuel usage seems like it is high to me...
  4. K

    Mercruiser 350 MAG MPI missing only at 3000 rpms

    If I shower down quickly I can essentially get past the engine missing. It still only occurs under normal throttle up to get on plane in the lower rpm ranges. Then once you power back down off plane it occurs again in same rpm range. So it seems to me it's not really associated to the engine...
  5. K

    Mercruiser 350 MAG MPI missing only at 3000 rpms

  6. K

    Mercruiser 350 MAG MPI missing only at 3000 rpms

    What are thoughts on this plug after roughly 4 to 6 hours of use?
  7. K

    Mercruiser 350 MAG MPI missing only at 3000 rpms

    Kenny - did have a new rotor. They are telling me they put on the usual AC 41-932 platinum plugs. I'll have to try to look at one and verify. In your issue, you put the OEM in but had ro go to like a NGK irridium plug?
  8. K

    Mercruiser 350 MAG MPI missing only at 3000 rpms

    Updates: If I shower down quickly I can essentially get past the engine missing. It still only occurs under normal throttle up to get on plane in the lower rpm ranges. Then once you power back down off plane it occurs again in same rpm range. So it seems to me it's not really associated to the...
  9. K

    Mercruiser 350 MAG MPI missing only at 3000 rpms

    Unfortunately this is not my issue after testing.
  10. K

    Mercruiser 350 MAG MPI missing only at 3000 rpms

    Update: I ran boat at night. Did not see any wires arcing against block. I did have the old 50amp fuse with yellow flag, I bypassed that and nothing changed. It now seems like I have an intermittent high pitched slapping/firecracker popping even at very high rpms. It reminds me of the sound my...
  11. K

    Mercruiser 350 MAG MPI missing only at 3000 rpms

    Thank you. I will check this out. Funny thing is I did have a new alternator put on. I bought the boat and had delivered. Never ran it personally before i had it serviced. Took it to shop and they made all the repairs above. So I can't compare before and after.
  12. K

    Mercruiser 350 MAG MPI missing only at 3000 rpms

    2009 Harris Grand Mariner 250 SEL Tritoon Mercruiser 350 MAG MPI Bravo III serial: 1A335811 300 hours Engine misses/hiccups only in a certain RPM range around 3000 to 3500. At idle and higher throttle it seems to run fine. It only misses or hiccups in that middle power range on throttling up...
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