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    2005 Mercruiser MPI 5.0L misfiring(?) when in gear, idles fine

    Thank you! I will check the muffler, although a very preliminary check today with a stethoscope suggests that the noise is coming from somewhere near the rear (possibly). To answer your question about the plug part number, I put in 8 new NGK BPR6EFS plugs. They are not iridium but it looks...
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    2005 Mercruiser MPI 5.0L misfiring(?) when in gear, idles fine

    Yeah it's so weird. The strangest part is that this noise was NOT there last time the engine ran not even a week ago. I am trying to think through what I actually touched on this motor recently.... spark plugs, plug wires, spark arrestor, distributor cap.... I really think that's it. It's so...
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    2005 Mercruiser MPI 5.0L misfiring(?) when in gear, idles fine

    Hi all, First, I want to thank everyone who has helped with this so far. I completely redid everything "downstream" of the coil and the engine was able to fire up. I am not convinced that I would have been able to get this going without help, and I want to express my gratitude to you all...
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    2005 Mercruiser MPI 5.0L misfiring(?) when in gear, idles fine

    Ooops! Yes, good catch... I meant: 1) I feel like I have very fast consistent spark off the coil.... 2) Yeah when I sometimes DO get spark off the plug, it's not very often and it's definitely orange. I'll edit my original post now to prevent future confusion but I appreciate the catch...
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    2005 Mercruiser MPI 5.0L misfiring(?) when in gear, idles fine

    First off, I might be a hostile witness.... I would consider it more like an "accidentally ignorant" witness but I think the end result is the same :) I feel like I have very fast consistent spark off the coil but I will take a video to confirm, so other can see the timing and double check my...
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    2005 Mercruiser MPI 5.0L misfiring(?) when in gear, idles fine

    Thank you! This distributor actually has a repair plate already, it just wasn't on for this picture as I had to remove all of that to get the cap off. I think I misspoke... I didn't mean to make it sound like the cap was moving. By "very little play" i mean more like I felt like I could maybe...
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    2005 Mercruiser MPI 5.0L misfiring(?) when in gear, idles fine

    Thanks all. Some responses for you all here.... I have verified that the rotor spins... kind of. The first thing I did when I got to the boat today was pull the dizzy cap off and after checking the compression in all cylinders, the rotor was in a different position. So it moves at least a...
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    2005 Mercruiser MPI 5.0L misfiring(?) when in gear, idles fine

    Haha yeah, I definitely confused things with my "custom" numbering! My suspicion is that when I go to match up the wires with your diagram, they will be either very close or right on as the boat was running pretty well before. Whatever this issue is, it's something that could progressively get...
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    2005 Mercruiser MPI 5.0L misfiring(?) when in gear, idles fine

    Thanks. Just to confirm.... that distributor photo that was in my post followed my (almost certainly incorrect) numbering on the engine diagram that was also in my post. So I think I confused things by using my own numbering and just tossing it out there. Can I confirm that this is the correct...
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    2005 Mercruiser MPI 5.0L misfiring(?) when in gear, idles fine

    Thanks for saying this! I appreciate the pep talk and the reassurance that at least one person appreciates all the detail... sometimes I worry that people see a wall of text and find it annoying :) Anyways, I have more information. Three new pieces of info: 1) Compression test seems good...
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    2005 Mercruiser MPI 5.0L misfiring(?) when in gear, idles fine

    Ok, so new information. I went down today with a spark tester. I tested a few plugs and was getting no spark. I tested the wire coming from the coil to the distributor and I was getting nice healthy spark coming off the coil. So, the issue must be somewhere between the coil and the...
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    2005 Mercruiser MPI 5.0L misfiring(?) when in gear, idles fine

    ok, I am going down tomorrow to check all of this. My understanding is that: My engine was running, but kind of slowly lost the ability to run over about 10-15 minutes of running time. I tried starter fluid in the spark arrestor which points to something other than fuel, which leaves: spark...
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    2005 Mercruiser MPI 5.0L misfiring(?) when in gear, idles fine

    ok, thanks. I'll do that. Just to confirm a few things (and some new information): 1. By spark gap tester, do you mean an inline spark testing light, or one of those testers that actually has a gap for the spark to jump? I have both so happy to test both. If you mean the one with the actual...
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    2005 Mercruiser MPI 5.0L misfiring(?) when in gear, idles fine

    Pretty annoying update... now the motor won't start at all. The only thing I can think of is that for a few days I've been running it off of an auxiliary tank (one of those 6 gallon red outboard tanks). I can't imagine this would make it not start. A hose comes out the built in tank and goes...
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    Flushing Sea Ray 250 Sundancer in salt water... How To, and is it necessary?

    Oh I didn't realize it was a whole "send to the lab" thing! I will have to do that, thanks for the pointer. I will also keep up with maintenance as you suggest. Thank you
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    2005 Mercruiser MPI 5.0L misfiring(?) when in gear, idles fine

    @alldodge Yes, I have mechanical controls. When you say scan the motor for codes, do you mean like with an OBD-type of scanner? Is there an OBD port on these, or is it some specific mercruiser thing? Thanks for all the info. I will check the easy stuff first.... new gas from an external...
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    2005 Mercruiser MPI 5.0L misfiring(?) when in gear, idles fine

    Oh! I don't think it's that I don't want to provide it, it's just that usually folks want the serial number range and that's good enough :) Just a simple misunderstanding, glad I asked. My full serial number is 0W611224
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    2005 Mercruiser MPI 5.0L misfiring(?) when in gear, idles fine

    Well, I have new information. I put a little seafoam through (gas and a little in the oil) just to clean it out, give it the best chance of running well. Ran it for a few mins the other day just to get the seafoam through the system and it ran like normal, minor misfires but generally okay...
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    2005 Mercruiser MPI 5.0L misfiring(?) when in gear, idles fine

    Darn.... is this cap compatible? I spent like $180 on a mercruiser brand cap (or maybe it was sierra or something, either way it was well over $30). Oh well, live and learn I guess. Good to know for next time
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    2005 Mercruiser MPI 5.0L misfiring(?) when in gear, idles fine

    Ah yeah, I might not have the right terminology but I definitely have the crab cap, I had a new one put on like 2 weeks ago :) 0W61xxxx
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