Search results

  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.
  2. 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
  3. W

    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?
  4. W

    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...
  5. W

    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...
  6. W

    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...
  7. W

    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...
  8. W

    5.0 mpi backfiring through exhaust. Won’t start

    Engine serial number is m367508 2005 5.0 mpi Working on my new boat and the port engine is giving me trouble. Finally got gas to it and it sounds like it wants to start but only backfires through the exhaust periodically. My question is if this would be a possible symptom of spinning the motor...
  9. W

    5.0 mpi runs rough when wet

    Can’t seem to track this down but noticed when the engine gets wet it runs rough. Low power, poor fuel mileage. Checked plugs, wires, cap and rotor replaced twice. Good fuel. Clean filter. When I left the engine cover off and let everything completely dry for a few days it was able to run 20...
  10. W

    Bravo air operated drain.

    One of my engines on the new boat has this cylinder with air lines as part of the water pump. I broke the top line off removing it. Can I delete this system. My other engine just has the 2 water lines on the back. What’s the purpose of this system?
  11. W

    Bravo 2 water pump impeller

    So I just purchased a boat with twin 5.0 mpi engines with bravo drives. My other boat has the same engine with an alpha one. Does the bravo drive have an internal impeller like the alpha one or is it just the water pump on the engine that needs service? What differences are there between the...
  12. W

    350 mercruiser stalling when shifted into gear

    My other boat project is giving me trouble. Got it running with help from here but now it shuts down when I go to shift it into gear. It’s a mercruiser 350 with the 2 barrel carb. Alpha one gen one drive. That’s all the info I currently have on this one. This is being tested on the hose in the...
  13. W

    5.0 mpi bogging and backfiring at high rpm

    Had my boat out for an offshore fishing trip. Ran 50 miles out no issue. Coming back about halfway it started dropping rpms and backfiring. It would then run ok for a bit then do it again. Then it cleared up and ran the last 15 miles with no issues. Fuel filter was good with no water or other...
  14. W

    Fuel pump issues

    So I’m helping someone with their new “free” boat. It’s a late 80’s model with a merc 350 with the thunderbolt v ignition and gen one alpha one drive. I can’t read the serial number anymore. Problem is that it started pretty readily after a tuneup and fluid change. Let it run a bit and it died...
  15. W

    Mercury wear pads missing cause of vibration?

    So for the moment I’ve got everything working as it should on my boat. Merc 5.0 mpi with an alpha one gen 2 behind it. My question is that at low rpm in gear the boat has a slight vibration to it that goes away with a little more rpm. The drive is a new sei marine unit but I’m pretty sure it did...
  16. W

    Where is this water coming from?

    Got her started. What have I got here?
  17. 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...
  18. 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...
  19. 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...
  20. 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...
Top