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  1. M

    Mercruiser 4.5l low vacuum, WOT 4350 and higher fuel consumption

    For people following along, I would never advise a cylinder drop test be done by pulling spark plug cables on a EFI engine. Unless you have a waste spark, non cat engine like @damo79 has. When doing this test, it will work best around 1500 RPM under load. Don't bother looking at fuel burn -- the...
  2. M

    Mercruiser 4.5l low vacuum, WOT 4350 and higher fuel consumption

    A few things I should point out for future reference. @damo79 has a DTM engine not the DTS engines that @tpenfield has. A DTM engine has a mechanical throttle control at the helm and a mechanical throttle and shift cables going back to the shift plate on the engine. Also this is a non cat...
  3. M

    Volvo Penta V6-240 Fuel High Pressure Dropping to Zero

    First --- thank you @Biz603 for responding! Did you put the boat away with some sort of stabilizer of conditioner in the fuel? And maybe sitting and soaking all winter freed up the HPFP? This one drove me CRAZY and I have always wanted to be sure what fixed it.
  4. M

    Mercruiser 4.5l low vacuum, WOT 4350 and higher fuel consumption

    No I can't, sorry. I understand your desire to see some published MAP numbers from MerCruiser --- I would to, but they don't that I can find. What I can find is numbers from engines that are similar to yours ----- but all of these engines have cats your engine doesn't have cats. The trouble...
  5. M

    Mercruiser 4.5l low vacuum, WOT 4350 and higher fuel consumption

    Hey Ted, Are you using the graph function to see these numbers?
  6. M

    Mercruiser 4.5l low vacuum, WOT 4350 and higher fuel consumption

    Yup, my claim to fame was two things. I have made or seen just about every mistake ---- once. I could handle the most "troublesome" customers with a smile. But I will admit that I once told a V.P. of the largest boat builder in the USA that he couldn't use his boat 4th of July weekend because...
  7. M

    Mercruiser 4.5l low vacuum, WOT 4350 and higher fuel consumption

    I don't see this as a waste of time. I look at it as a learning experience. Hopefully people who read this thread will see the importance of complete and correct troubleshooting. But yes, I would love to see the resolution to this problem. But I have my doubts, I've had many customers like this...
  8. M

    Mercruiser 4.5l low vacuum, WOT 4350 and higher fuel consumption

    Have you ever been part of a boat test for a magazine? I have, and I sure wouldn't use what they published as a substitute for actual testing. The people who do these are trying to sell boat --- plain and simple. I've read the article (that's how I found out it takes 3-4 months from the test to...
  9. M

    Mercruiser 4.5l low vacuum, WOT 4350 and higher fuel consumption

    But it is an modern engine, it doesn't need knock sensors for one thing. First, there is a possibility those numbers are corrupted. Second, what is happening at 2500, 3500 etc. Your complaint seems to be low WOT RPM and excessive fuel usage. We need to see all the RPM range.
  10. M

    Mercruiser 4.5l low vacuum, WOT 4350 and higher fuel consumption

    Your System Voltage is dropping to 8.5v during cranking. That is VERY bad according to Mercury Marine. With the PCM112 they want no lower then 11.5v but will accept 11.0v. I don't care what the internet says, I get my info from Mercury Marine. Funny story about the internet. Awhile back I...
  11. M

    Mercruiser 4.5l low vacuum, WOT 4350 and higher fuel consumption

    I can't edit post #116 When I said. "Any drop above 0.5v is bad. So 0.4 while at full charging is the only good number you have!" I should have been clearer. during cranking the voltage in the battery will drop more then 0.5v. But this is in the battery, not in the wires and connections. Also...
  12. M

    Mercruiser 4.5l low vacuum, WOT 4350 and higher fuel consumption

    I tried to answer all your questions and give you my insight. If I missed anything let me know and I'll try to help.
  13. M

    Mercruiser 4.5l low vacuum, WOT 4350 and higher fuel consumption

    I guess that would depend on advanced or retarded. From my understanding this usually happens during a extreme event. Like a hard under water strike or wake jumping. But lets fix the easy stuff before looking at the odd ball stuff. Yes the manuals can have some issues. Note that Mercury doesn't...
  14. M

    Mercruiser 4.5l low vacuum, WOT 4350 and higher fuel consumption

    Yes there is a crank key, but does it include the reluctance wheel or is it just for the cam gear and harmonic balancer. I can't tell.
  15. M

    Mercruiser 4.5l low vacuum, WOT 4350 and higher fuel consumption

    This engine never really gets stabilized enough to look in depth. The fuel and ignition tables are changing to often for me.
  16. M

    Mercruiser 4.5l low vacuum, WOT 4350 and higher fuel consumption

    Yes I looked at the chart --- it's the same chart that's in all the manuals since the beginning of time. I noted that it starts with "most engines" seeing as that chart has been around since points and carbs, I would say you don't fall under that category. I also noted that under low vacuum...
  17. M

    Mercruiser 4.5l low vacuum, WOT 4350 and higher fuel consumption

    I haven't had much time today to spend on this, but I did want to cover the most important part ---- electrical system. There are a lot of checks, calculations and choosing of all the tables that happen during starting, so correct power is critical. This is why I recommend that during starting...
  18. M

    Mercruiser 4.5l low vacuum, WOT 4350 and higher fuel consumption

    They didn’t mention any problems with the keyed ones in school, good to know. I’m guessing that at least you could poke something through the CPS hole and get it to wiggle.
  19. M

    Mercruiser 4.5l low vacuum, WOT 4350 and higher fuel consumption

    The other side of that coin. These newer engines will alert you before they ever get that carboned up, so it will never happen. Sold a new EFI 10 hp last month, we wouldn’t take his 1994 10hp on trade because it was too old Even though “it runs really good”. He called two weeks later and was...
  20. M

    Mercruiser 4.5l low vacuum, WOT 4350 and higher fuel consumption

    Funny thing—- maybe because I understand the new systems, I find them easier to diagnose. Especially if it has cats. Another funny thing—- even though I work in an industry that turns fossil fuel into CO. I still have some pretty strong opinions about pollution and what it’s doing to the...
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