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  1. M

    Hesitation/RPM Hunting on 496 Mag HO

    P Maybe not a solution in your operation but my 350mag had a very similar sounding glitch. Tried several ideas. The cure seems to have been the replacement of the high pressure pump and regulator. That job requires attention to detail during assembly. Runs very well now. And I worked it HARD...
  2. M

    350mag Mpi

    Made it to the river and back today. All the latest efforts have made a bit of positive change. Saw 50mph one time but I think the wind was helping. 47 tops on all other WOT runs. Oil pressure stays up 40-50 now unless I really try to screw up the shft/neutral operation but even then it stays up...
  3. M

    Melted coil feed wire = Bad Pertronix?

    Maybe not even the problem but I keep an extra one of these and some zinc thermal paste in the glovebox just in case.
  4. M

    Melted coil feed wire = Bad Pertronix?

    I have ATK marine 351w in my 67F100 with same ignition system. Started out good then went bonkers twice. Go to Summit Racing sight and do some digging. You will find a correct ohm (much better) coil and with a little more digging a replacement “module” (very small price) and I bet it will work...
  5. M

    350Magmpi

    Steering slack issue resolved. I was suprised to see clean bolt and nut instead crusty mess like I have seen on other videos.
  6. M

    350Magmpi

    Made a little more progress. Managed to get some ATF pressure injected into ends of all three cables. Adjusted with rigging tool and now the low idle shift stall is gone as far as I can test on the trailer. Throttle handle works a lot better. Oil pressure after 1/2hr so far is still hanging...
  7. M

    350Magmpi

    So I convinced the fuel cooler to get back into its nest with some extra thermal paste. Starts and runs. Warmed up to same 165ish water temp as during our last lake trip and 50ish oil pressure prevails with 42ish fuel pressure and 16-17”in MAP. Ran it for about 15 minutes beyond that at around...
  8. M

    350Magmpi

    So I finally got the fuel cooler rig out. Found two orings on the elbow were shaved so I am glad to discover and get that resolved. The little regulator had thread tape around the threads but way too much of it ended up inside the regulator. Dought that was helping anything. The tiny screen...
  9. M

    350Magmpi

    So while I wait for the new fuel pump regulator I polked around some more. Access to the port side pump will be a fine chore. I carefully removed the vac line from the regulator and sure enough it is breached and rusty inside the damaged portion of hose and definately loosing vac. Hopefully this...
  10. M

    350Magmpi

    Fabricated oil change extraction rig today with some scraps from around shop (old weed spray tank) and used the A/C vac pump. Oil was decent; not really burnt or stinking of gas or frothed with water but pumped 8-1/2 quarts out. Looked in parts book and engine manual and looks like it has the...
  11. M

    350Magmpi

    Finally got the boat shed roof on. Recieved and studying manual 36. Gathering test t-pins and fluke multimeter. Neighbour’s v-6 boat acted up and cost him a starter and oil pressure sending unit. I think I will give his technician a try when we start planning the gimble update. I do want to try...
  12. M

    350Magmpi

    Well one way of looking at that is maybe if i break it bad enough the computer will report something or engine will quit bad enough to finally find something to fix. So far any thing I have tinkered with has had no continuous effect (good or bad). I figure the cool fuel pump is screwed anyway...
  13. M

    350Magmpi

  14. M

    Mercruiser EFI Stalling and Surging Symptoms at Idle

    I am new to this vocation. My 350mag mpi sounds like it has been in the same water as yours. My fist encounter with boat service was the place close to where I bought the boat..(strike one), second time was my next closest to home and strike two with no codes to read, all just a bunch of...
  15. M

    350Magmpi

    Well only for testing purposes. I aint about to launch it till all this irractic idle and on plane hesitation and intermttent growling issues are handled. Once I get into the manuals tomorrow I plan to perform a full yearly service event so I can start a record book. All my piddling to this...
  16. M

    350Magmpi

    I did remove the water seperator filter and carefully poured out what I could. Bout a 1/2 teaspoon of untrapped water is all I could capture but yeah I pretty sure this rig has suffered a water intrusion event. And contaminated fuel. I managed to pull my little Optimax out of the grave so I...
  17. M

    350Magmpi

    Books made today so I can start a more focused approach. Still dont see how the vacuum source from intake brings fuel pressure down…what part is failing…which regulator or pump. No data on why the IAC solenoid is so hot so quick. Why does a plug removed from fuel injector not show some fault. I...
  18. M

    350Magmpi

    IAC solenoid is toasty. Idle is too low (560). Out of water (trimmed in most of the way) RPM advanced to 4000 just to check console tach and see if I could get oil pressure to fall off at idle. Second run got a long tone beep (possible rpm exceedance sensor not working IDK). Oil Px still okay...
  19. M

    350Magmpi

    Got the Rhinda gadget working…..more questions.
  20. M

    350mag Mpi

    Hi folks, 100degrees today so little bit of prep work for new boat shed and yard work was about it. However I did some more poking around in the engine bay. Attached are a few pics of plugs I cannot identify. Books soon I hope. One pic is of a tagged harness that says diagnostic (2006) with...
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