454 MAG MPI issues. Won't rev under load.
04-17-2014, 01:30 PM
#25
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I had a similar problem with one of my 502 mags turns out it was a bad coil still ran fine when not under load but when loaded up it had no power. no miss while running either. it had to have been missing while getting on plane but i couldnt hear it....
04-17-2014, 01:56 PM
#26
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Does it feel like a rev limiter,,,, or just no power?
Gonna sound silly,,,, but unplug your gear oil reservoir bottle sending unit
Gonna sound silly,,,, but unplug your gear oil reservoir bottle sending unit
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04-18-2014, 08:13 AM
#27
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Yoda, I will check into that for sure. I plan on doing a complete tune up this weekend (Cap, rotor, wires, plugs), I think I'll go ahead and throw a new coil on there. Obnoxus - I have hear of that sensor going bad and not allowing the motor to rev up, will unpluggin it simply bypass it?
04-18-2014, 08:26 AM
#28
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correct, unplugging bypasses it,,,, you NORMALLY get an alarm along with it,,,,, but its worth looking at
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04-18-2014, 08:35 AM
#29
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A few years ago I help a friend change head gaskets and install a procharger on his 454mpi. It idled and ran find on the hose but once it was in the water under load, it didn't have any power to get on plane. after hours of messing around with timing, plugs, wires, cap, and troubleshooting, we found an injector plug didn't get snapped all the way on and was just sitting under the plenum. Plugged it back in and bingo, it ran great. Not saying that is your problem, but just one bad cylinder or injector can cause way more power loss than you would think it does and it may not sound like it is missing. I believe just unplug your gear oil reservoir bottle sending unit to bypass it. I do have a VST off a 96 or 97 454mpi if you really want to go that route. It hasn't been on a boat for 10 years, but worked fine when it was removed.
Problems like this are a pain to find, so Good luck and don't sink the boat!
Problems like this are a pain to find, so Good luck and don't sink the boat!
