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  1. W

    IAC Duty cycle explanation

    On my engines the IAC is showing a duty cycle of around 30%. When the engine is under load at anything higher the duty cycle is at or near 100%. Normal or no? I assumed the IAC should be not doing anything above idle.
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    MAP pressure readings

    thank you. Next up is the duty cycle of the iac stays pretty much around 99.98% at higher rpm and aound 30%at idle. Is this information somewhere in one of the manuals so I can look it up instaed of coming here every time I have a question? I have a few of the manuals.
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    Tachometers not working correctly

    Hey just an update on this one. Im not sure how they are related but I connected the pcv valves that i neglected to hook up when I reassembled everything on these engines and both tachometers started reading correctly. Anyone know how or why this is? No other changes were made to the engines...
  4. W

    MAP pressure readings

    Finally got my engines hooked up to the diacom software and was reviewing the data and im trying to see if the readings are ok. The MAP pressure is right around 6 at idle and goes up to about 13 psi at 4300 rpm under load on the water. Does that sound right? Engines are mercruiser 6.2 mpi 2002
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    pcv valve and vent tube routing

    Does anyone have a picture of the tubing routing from the pcv valve and the other vent on the other valve cover on an mpi engine?
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    Fuel pressure low.

    Im not sure if this is correct But i read elsewhere that the fuel pressure will be lower running at idle and should increase running under load in the water. Does that sound correct? Im going to get it on the water today and run the software on both engines but if thats true than my issue may...
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    Fuel pressure low.

    Ill get it hooked up and post the numbers from diacom. going to verify with a second gauge as well. The ecm has no effect of fuel pressure though right?
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    Fuel pressure low.

    Yes on the ecm. That was ordered new from mercury based on the original serial number but for a 6.2 through John at boats unlimited. The timing was set correctly as far as I can tell.
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    Fuel pressure low.

    seems to be lacking power. I can get another gauge to double check what im seeing as well. serial number of the original engine is m367508. was a 5.0 mpi. Swapped parts to a 6.2 long block and got a new ecm to complete it. Its tough to really know for sure but im looking at the original...
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    Fuel pressure low.

    Im trying to track down my low fuel pressure issue. It is a 6.2 mpi with both the lift pump and high pressure pump in the system. When I turn the key on and the pumps run I get 43 pounds on the gauge and when they stop it drops to 38-40 pounds and stays there, When it is running im only...
  11. W

    Tachometers not working correctly

    No other ideas? Ill look into the gauges themselves but where do they read from on the motor side?
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    Tachometers not working correctly

    I have many small issues to sort out on my project here and my latest is non functional tachometers. I have a pair of 6.2 mpi mercruisers. one is a 2002 and one is a 2004. at least that is what the computers are now. These were built from a couple 5.0 mpis that I swapped the parts onto new...
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    Engine alignment problem

    By the looks of that thread the stainless washers are optional. That may be just enough to lower it to line up correctly. Ill remove them and report back.
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    Engine alignment problem

    Here it is. I removed both engines from my boat a couple years ago and just got to finishing and installing the new ones a couple weeks ago. First engine went in no problem. Minor adjustment needed but the alignment tool slides in. Engin 2 goes in and it appears to be sitting slightly too...
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    5.0 mpi to 383 conversion thoughts?

    Thanks for that. Still researching engine builders.
  16. W

    5.0 mpi to 383 conversion thoughts?

    Can you direct me to the places that can flash the ecu? Just getting costs together at this point.
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    5.0 mpi to 383 conversion thoughts?

    It’s got bravo 2 drives. No more height clearance for taller engines. They almost touch already. Lol. Where can I get the ecu flashed. The engine shop said they will run but not to their full potential with the current ecu.
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    5.0 mpi to 383 conversion thoughts?

    Looking for ideas and concerns with this idea. I’ve got a pair of 5.0 mpi engines in my boat and want to go bigger. Looking at getting a pair of 383 stroker long blocks and swapping the mpi intake and all other parts over to the engines. Will the ecu work or would I need a new ecu for each? Can...
  19. W

    5.0 mpi backfiring through exhaust. Won’t start

    Nice thing about 2 engines is I can swap parts. Lol. I’ll check out the iac
  20. W

    5.0 mpi backfiring through exhaust. Won’t start

    What is the correct order for the wires on the cap? Th
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