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  1. M

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

    Another thing. Do you have the HIN and serial numbers for the drive and transom? With those I might be able to see how this boat came from the factory and what engine was in it then.
  2. M

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

    Something else just popped into my head. I have very little experience with non OEM props. You have a non Mercury prop. I don’t sell them, don’t use them and have never been in a situation where Mercury didn’t have the best prop for a Mercury application. They aren’t the cheapest but I do...
  3. M

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

    I thought you said you dropped 2” in pitch? Generally speaking, a little boat like this, that should have a 19” prop will become a dog if you put a 21p on it. And will become a rocket ship with a 17p. 4” change will make a huge difference. The drive, yes any good tech can feel tight backlash or...
  4. M

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

    My money is still on. propping starting voltage fuel
  5. M

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

    My guess is that vacuum changing fuel pressure by about 10% isn't going to change GPH by 30%. Excessive fuel use is a symptom, not a cause. If you are worried about fuel pressure, I recommend you follow the troubleshooting chart T-3 in section 1D of the engine service manual. If the engine is in...
  6. M

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

    Misfire counters show up in Diacom, but because this engine doesn't have a cam sensor and cats --- any info you see will be bogus. This engine has a 56x reluctor wheel. So when the proper conditions are met it will adjust fuel and timing to each cylinder separately. It will try to keep each...
  7. 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...
  8. 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...
  9. 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.
  10. 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...
  11. M

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

    Hey Ted, Are you using the graph function to see these numbers?
  12. 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...
  13. 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...
  14. 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...
  15. 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.
  16. 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...
  17. 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...
  18. 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.
  19. 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...
  20. 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.
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