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  1. vroom ZOOM

    454 mag mpi chuggles/stalls

    Put the voltmeter on the tan wire from the ECM with the IAT unplugged. Started the engine and the reading stayed around 5.2 volts. Also wasn't able to get the meter on the wire with the sensor plugged in but here are the diacom readings from the sensor with the engine running. ECT sensor paints...
  2. vroom ZOOM

    454 mag mpi chuggles/stalls

    I have a rec file. Will send it to you via pm
  3. vroom ZOOM

    454 mag mpi chuggles/stalls

    I only swapped the upper part of the intake with the sensors and throttle body. And yes new gaskets if any were torn. No parts swapped had any effect, except for the injectors. Today I decided to try swap injectors again. What do you know, the engine fired up and ran perfectly for about 2...
  4. vroom ZOOM

    454 mag mpi chuggles/stalls

    took them out, looked a little sooty but all the same.
  5. vroom ZOOM

    454 mag mpi chuggles/stalls

    I dunno... this is what mercruiser calls it... straight from the manual!
  6. vroom ZOOM

    454 mag mpi chuggles/stalls

    oh jeez.... Just spent the entire day in the engine room testing every possible circuit on the wire harness, and no luck. I even took some pins out of the ECM plug and did static tests on the injectors, each one pulled 0.75 amps through the wire harness and directly, indicating a good...
  7. vroom ZOOM

    454 mag mpi chuggles/stalls

    Well DAMN! I spoke too soon. As soon as the boat hit the water, the motor is back to its old self. I checked the contacts on the injectors and now that doesn't help. I swear this thing is cursed. Restart the suggestions!
  8. vroom ZOOM

    454 mag mpi chuggles/stalls

    Well everyone, it is FIXED!!! FINALLY! you are not going to believe what it was... The fake injectors had the pins in the connectors slightly off center, and they made better contact with the terminals in the socket that had taken a "set" and had a loose connection. So the fake injectors made...
  9. vroom ZOOM

    454 mag mpi chuggles/stalls

    no unfortunately I dont. I really didn't record anything as the engine ran amazing. Will do that today.
  10. vroom ZOOM

    454 mag mpi chuggles/stalls

    no, iac is around 50 counts.
  11. vroom ZOOM

    454 mag mpi chuggles/stalls

    Ill crank it up today and post the graph.
  12. vroom ZOOM

    454 mag mpi chuggles/stalls

    Well here is a REAL head scratcher: I put the cheap knockoff set of injectors in it that the other running engine had last week and that made the engine run PERFECTLY. I thought that the injectors were bad so I ordered a new OEM set. I put them in and it runs like crap. A few hours ago I decided...
  13. vroom ZOOM

    454 mag mpi chuggles/stalls

    ok, I ran the engine a couple of times and generated some graphs.
  14. vroom ZOOM

    454 mag mpi chuggles/stalls

    Yes I plugged the pcv valve when I put the vac gauge on it. No change. Will try it again and post screenshots of diacom. I tried the harness from the working engine, no change.
  15. vroom ZOOM

    454 mag mpi chuggles/stalls

    Ok, this thing has me beat. 2000 454 mag mpi (mefi3). starts, then when settling to idle it chuggles and stalls. Brand new longblock. old one also did the same thing. I tried known good ignition modules from properly running engines, reset the distributor to #1 tdc countless times, tried a...
  16. vroom ZOOM

    mercruiser 454 MPI Horizon stalling

    I think I will just buy another IAC for $50, they seem to be cheap and readily available. I am pretty darn sure those are adjustable rockers, I think when whoever rebuilt the heads they changed to adjustable rockers. They have the stud with a nut. There was a yogurt container with the old...
  17. vroom ZOOM

    mercruiser 454 MPI Horizon stalling

    Hello Working on this interesting case of a motor. When I started messing with it, the front timing cover was removed, the cylinder heads looked unpainted and had adjustable rockers in them, and the intake manifold had a couple of new bolts. Additionally there where new manifolds and elbows on...
  18. vroom ZOOM

    Painting drive with delfleet

    Hello, I want to try another paint/process for one of my transom plates. I dropped it off to have it laser cleaned so its basically going to be perfectly clean from paint corrosion and grease. I want to etch it with muriatic acid, and then apply alodine. For paint, has anyone tried painting...
  19. vroom ZOOM

    Low Fuel Pressure 2005 Mercruiser 4.3L MPI

    What is the fuel pressure doing if you turn on the pump? What is the reading? What is the reading as soon as the pump turns off? How fast does the pressure drop to 0 after the pump turns off? Did you check for WATER in fuel at the rail?
  20. vroom ZOOM

    Low Fuel Pressure 2005 Mercruiser 4.3L MPI

    Yes. I think you can also use a 3/8 NPT plug. let the pump run a few cycles before looking for air in order for the air that got in while messing with it to get purged. also MAKE SURE to check for water in fuel.
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