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  1. W

    Ignition wiring questions.

    Ok. So now I’m at the 90 amp fuse. Pulled it off bc it was terribly corroded. Took it in the shop and cleaned it and tested it. No continuity. How could I have had voltage to the wires above it if it’s not showing any continuity. Any thoughts. I’m of course going to replace it before doing any...
  2. W

    Ignition wiring questions.

    Voltage at the key goes to 0 when I turn it. I gotta check the other 2
  3. W

    Ignition wiring questions.

    No change
  4. W

    Ignition wiring questions.

    Update. Disconnected the “new” alternator and now I get 12 volts but still nothing when I turn the key.
  5. W

    Ignition wiring questions.

    Also got 3 volts at the breaker on the engine and at the alternator power post.
  6. W

    Ignition wiring questions.

    I’ve got a bay liner trophy from 1998 with the 5.0 mercruiser engine and alpha one drive. Just getting it going for the season and nothing at the key. Battery is tested and good. The kill switch seems to be good. I attempted to jump it and leave it disconnected since I didn’t know if it was a...
  7. W

    5.0 mph belt routing

    Lol. I figured as much. As soon as I figure it out I’ll report back. Just needed the routing diagram to confirm I got that part right. Thanks.
  8. W

    5.0 mph belt routing

    Yes. All the way. I’ve had this on and off a few times over the years. Other than the new alternator I can’t figure out what’s going on.
  9. W

    5.0 mph belt routing

    That looks like how it came off but the belt seems to be about an inch short now. Can’t figure out why. I’ll probably get another longer belt and run it like this. Only change was the alternator and I reused the original pulley. Alternator mount was no different so I dunno.
  10. W

    5.0 mph belt routing

    Ok. Not sure what happened but I replaced my alternator and now the belt is too short. Lol. I’m sure I’m doing it wrong but can’t find any diagram where it’s correct. The motor is a 5.0 mph serial number 0m670725. I changed the pulley to the original one because the new one was bigger but still...
  11. W

    blocked manifold? 5.0 mpi mercruiser

    Just trying to confirm what ive already found before i order parts. Have had an overheating issue for a while now and think ive found it. Boat runs hot at higher rpms. Did the clear hose test. No bubbles. Did notice the last time out the left riser was too hot to touch but the right was...
  12. W

    Automotive vs marine thermostat

    So haven’t definitively solved my overheating problem but thought about the fact that I used an automotive 160 degree thermostat last spring and ran mostly in salt water with my raw water cooled engine. Is there any difference in the materials used or flow allowed? The motor specs are 2003 5.0...
  13. W

    mercruiser 5.0 mpi slowly overheating

    Got my boat out for a test run today and it runs great except that after about 30 minutes of running about 75% throttle it overheated. Shut it off for 3 minutes and restart. immediately cooled down. Ran a bit longer and the temp was slowly climbing again and I stopped but didnt shut it down...
  14. W

    Octane recommendation in 5.0 mph mercruiser

    I have been running 89 from the pump with ethanol bc I can find gas without it. I use Star tron additive to help with this. Is there any reason I couldn’t run 87 and get a little more? What’s everyone’s opinion on this?
  15. W

    Alpha one gen 2 bumped out of gear but stuck in gear?

    So i was cruising across the lake today at high speed and my drive sounded and felt like it shifted out of gear and back into gear suddenly while cruising. I immediately put it in neutral but the engine stalled. Cant turn like the drive is stuck in gear. I noticed recently that the drive...
  16. W

    98 Trophy 2352 top speed and fuel economy.

    So I finally got my motor back together and tested out several times on my local lake and I don’t think I could ask for more. It’s got the 5.0 mpi mercruiser with an alpha one drive running a 17 pitch revolution 4 prop and on the lake it’s topped out at 41 mph at 4700 rpm. At this speed I was...
  17. W

    5.0 mpi overheat at higher rpm.

    Finally got the heads back and on the boat. Runs great but at higher rpm it will overheat and wont cool off unless I shut the motor off for about 2 minutes and restart. Then the temp drops rapidly. Ive noticed if you are looking at the motor the left riser on the exhaust gets pretty warm...
  18. W

    Few questions about engine condition and parts differences. 5.0 mpi

    Ok so I left off with finding my heads were completely wasted. Deformed and Leaking intake valves and both heads cracked. After looking things over I found the water passages on the bottom or outer part of the cylinders as well as the heads were plugged solid with metal debris. I had to clear...
  19. W

    5.0 mpi losing power after warm up

    I figured i should just start over since im down to one problem and noticed more of whats happening with my motor. As stated in my previous post Ive completely removed and cleaned out the fuel tank, changed the cap, rotor, plugs , wires, fuel filter, all injectors, and oil change with...
  20. W

    Engine wont start in the water. Then loses power at full throttle.

    Hopefully someone can point me in a direction here. Ive done searches here and on several other sites but cant find a solution to my problems. First with the details. Ive got a 2003 mercruiser 5.0 Mpi with an alpha one gen2 outdrive. First problem. The engine starts no problem on land but...
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