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  1. tpenfield

    Compression test

    A cylinder leak test may be more revealing than the compression numbers. In general, your engine is OK, but not great. Did you do the compression test with throttle wide open? I like to do the compression tests with the outdrive off (can't always do this) and battery being charged...
  2. tpenfield

    Starting boat after 4 years - pre start steps

    It looks like the OP has not been back since posting. When they do, hopefully we will get an update
  3. tpenfield

    I/O (Sterndrive) Conversion to Outboards

    Looks like Honda has a 350 hp, no 300 hp. The weight is about 100-150 lbs more that the other single prop OB’s
  4. tpenfield

    I/O (Sterndrive) Conversion to Outboards

    one of my big ‘wants’ in a re-power is to have joystick docking. That puts Mercury at an advantage, because they have an integrated system that has been around for a while. I have not seen much in the re-power space and digital controls from Honda; not sure if they focus there. 🤔
  5. tpenfield

    I/O (Sterndrive) Conversion to Outboards

    I was wondering about the choice of engines . . . I expect that mercury will be the most $$$ and they are going to be V8 (4.6L) or V10 (5.7L), depending on power choice. Suzuki seems to own the re-power market . . . not sure if that is based on price or other factors. :unsure: The Yamaha and...
  6. tpenfield

    I/O (Sterndrive) Conversion to Outboards

    I’ve started using a bit more trim tab to get more stern lift. It makes a big difference.
  7. tpenfield

    I/O (Sterndrive) Conversion to Outboards

    Summer Update . . . I've been doing a little bit of research on the outboard engines. Planning on having Mercury, Yamaha, and Suzuki quoted. Key Spec's/Features 300-350 HP Twins Mercury is more of a known commodity . . . planing on the same feature set I have now with the I/O's (DTS...
  8. tpenfield

    Draining gas tank questions -- Is this thing a vent? How does my tank look in general?

    Late to the party . . . but Get a small hand pump meant for oil/gasoline. It will create enough suction to open the anti-siphon valve. #1 is your vent (allows air to go into the tank as fuel is used) #6 is a spare tap, most tank will have a spare, sometimes it is used as a return fuel line...
  9. tpenfield

    FANTASTIC web site !!

    It looks like bacon.com may be available. (y)
  10. tpenfield

    Starting boat after 4 years - pre start steps

    Was the boat properly laid up 4 years ago? The main things that I would do is . . . Take the spark plugs out and squirt some fogging oil into the cylinders, shoot a little fogging oil down the carburetor. Then with the spark plugs still out 'spin' the engine with the starter for a few...
  11. tpenfield

    looking at a 1990 thompson 260 fisherman

    there on some videos of fixing a Thompson 260 . . . I agree with the others, average quality boat now 36 years old, so about double of its life expectation.
  12. tpenfield

    454 mag mpi chuggles/stalls

    Yes, the thing I’m not in love with about the Diacom is that you can only graph 3 things at a time. In the recent test- I may be that the Map value increased because the iac opened up. anyway, I think the OP has the intake/throttle body to look at.
  13. tpenfield

    454 mag mpi chuggles/stalls

    It looks like the initial barometric pressure (Baro MAP) is 30 and the 'good' engine goes down to about 12. The 'bad' engine goes to about 8.5. It also looks like the 'bad' engine was able to keep running if/when the IAC moved all the way up to the 155 range, and so the injector pulse stayed...
  14. tpenfield

    454 mag mpi chuggles/stalls

    Here are some graphs from both the Good and the Bad engine . . . Good . . . . . Bad . . . . . I am seeing that on the 'bad' engine the MAP value goes down lower when the engine revs from the initial start and the IAC valve has to open more to keep the engine running. The lower value of the...
  15. tpenfield

    454 mag mpi chuggles/stalls

    It’s a beach day for me today. I’ll take a look at the files this evening . a good assumption may be that the ECU is responding to the sensor inputs. The question being, what is telling the ECU to make the injector pulse so short?
  16. tpenfield

    454 mag mpi chuggles/stalls

    Just comparing to my 7.4 LX data files. . . wondering about the IAC position . . . looks high on your engine. Comparing the data files of the good engine and the 'troublesome' engine may be helpful. Send them as you are able.
  17. tpenfield

    454 mag mpi chuggles/stalls

    You mentioned a new long block and the previous engine had the same issue. Did the intake manifold come from the old engine to the 'new' long block? (sorry if that was already discussed)
  18. tpenfield

    454 mag mpi chuggles/stalls

    Here are the engine speed, injector pulse, and MAP as a graph. Overall the injector pulse looks low. MAP also looks fairly low. Maybe send me a similar file from your 'good' engine for comparison. . .
  19. tpenfield

    454 mag mpi chuggles/stalls

    Here is a Diacom reading from my 7.4L LX engine at idle, similar ECT. . . . Notice the difference in injector pulse and the MAP
  20. tpenfield

    454 mag mpi chuggles/stalls

    It might be good at this point to list out the things that you have not replaced or swapped out with the other engine.
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