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5.0 OSi-E low power, unable to hit RPM & WOT.

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  • 5.0 OSi-E low power, unable to hit RPM & WOT.

    Background...I have been trying to troubleshoot this low power issue for a few weeks now. The motor while trying to get on plane basically stalls out at 3000 RPM until it finally gets on plane after about 10 seconds then maxes out at 4300 RPM. The boat is a Regal 2120 (21 foot boat I believe) and the engine is now a 5.0 OSi-E (serial 4012110198). The boat originally had a 4.3L GXi that I replaced in 2017 because it was ate up with salt water. So the outdrive (1.66:1) and prop (14 x 19) are the same as originally came on the boat so this thing should be giving us whiplash with the extra 45+ horsepower on the same drivetrain. In fact, in talking to Regal engineering, this is what they said:

    "The 2120 Destiny was built with a 50GXI. It used a 1.60 drive and a 21" prop. Top Speed was 53 MPH and O to 30 was 8.3 seconds on the one we tested. If he changes the engine the motor mounts will move forward of their present location by 4.5 inches.... he should be able to measure and see if the motor mount has an additional 4.5 inches but I believe it does. He could use the 1.66:1 drive he has but would likely need a 21 or possibly a 23" prop. Otherwise he would be on the Governor on the engine."

    I am not getting anywhere close. The boat sat in storage all last year since we moved and didn't have opportunity to get it out. Now this year, it just is not performing up to par.

    I bought MEFIscan to try and see what is going on. I have never used this software before so I am learning on the fly, but I don't see anything out of place...at least no codes, etc. I made a few runs today to get some data. I basically started at idle in gear and went to full throttle and then after the motor topped out (usually between 4000 and 4100 RPM, I then slowly brought the throttle back to idle. I made 10 or so runs and captured a few with MEFIscan and a few others with some different software that writes the data to a CSV file that can be opened by excel. I'll attach both sets of data to this message. I think the first couple of runs with MEFIscna, I was getting some errors so you see the data jump around a bunch, but the last 2 or 3 were pretty clean. Behavior was the same in all in any case.

    The one thing different today was I put on a 21 pitch stainless prop I had to see if it made any difference. The aluminum prop paint was not in the best shape so I wanted to see if a nice smooth prop made any difference. The only difference is that the motor maxed out 200-250 RPM slower than it did with the 19 pitch aluminum prop.

    I am hoping that something sticks out in this data that points to something I should check or look at. These runs were with just me and my wife (~450 pounds total), half a tank of gas (20-25 gallons), 6-8 gallons of water in the fresh water tank, maybe 150 pounds of other gear, and the 3400 pound boat. We had two other people on it last weekend that added maybe another 250 pounds and it was a struggle to get it on plane when they were in the back. I just remember this boat performing much better in 2017 after I put the motor in it. I followed the recommended break-in procedure for a new motor and babied it until 20 hours. After that, we had 10 people on it and pulled a tube with no problem. Now I am afraid to try and pull a tube. It starts fine, sounds fine, just seems to run out of steam.

    Before I put the motor in, I found low fuel pressure and found out the fuel pump had all the inside paint eaten away (typical Vovlo issue) so I rebuilt it and replaced the pumps. The paint had gotten stuck in the fuel regulator and I got it all cleaned out. Fuel pressure was right on target at 60psi after that. I have not checked fuel pressure this year and the old (treated) gas in it is gone now and I have run quite a bit of fresh 89 octane in it.

    My next steps are to check the compression and fuel pressure again. I'll need to borrow those tools. Any other items to check? Sorry for the long post, just wanted to give as much detail and background as possible. Any help would be appreciated.

    Thanks!!
    Attached Files

  • #2
    I have not checked fuel pressure this year and the old (treated) gas in it is gone now and I have run quite a bit of fresh 89 octane in it.
    Ayuh,..... Examine the Contents of the fuel filter, for anything but clean fresh gasoline,......

    Then replace it, 'n try a run,....

    Comment


    • #3
      Before I put the motor in, I found low fuel pressure and found out the fuel pump had all the inside paint eaten away (typical Vovlo issue) so I rebuilt it and replaced the pumps. The paint had gotten stuck in the fuel regulator and I got it all cleaned out. Fuel pressure was right on target at 60psi after that. I have not checked fuel pressure this year and the old (treated) gas in it is gone now and I have run quite a bit of fresh 89 octane in it.
      The motor is running good but unable to reach max rpm is my take away. If correct, find a marine fuel injector place to clean and flow test. Make sure they can test up to 6000 rpms.

      Before that, I would do a compression test
      94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
      95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
      07 Seadoo GTX
      Merc Adults Only VP Adults Only
      G-Dad always said "First Liar doesn't stand a chance"

      Comment


      • #4
        Originally posted by Bondo View Post

        Ayuh,..... Examine the Contents of the fuel filter, for anything but clean fresh gasoline,......

        Then replace it, 'n try a run,....
        I did empty the one on the boat now. It looked clean, but I did order a new one a couple days ago just to eliminate it. It should it will be in this week.

        Thanks!

        Comment


        • #5
          When was the diz cap last changed ?

          Comment


          • #6
            Originally posted by QBhoy View Post
            When was the diz cap last changed ?
            Not sure. The engine has about 190 total hours on it. I have put ~30 of those on it. I'll take a look at it and order one if it warrants.

            I really hadn't thought about that with everything being electronic, but good idea. Thanks!!

            Comment


            • #7
              Originally posted by lonewolf41 View Post

              Not sure. The engine has about 190 total hours on it. I have put ~30 of those on it. I'll take a look at it and order one if it warrants.

              I really hadn't thought about that with everything being electronic, but good idea. Thanks!!
              If it’s the crab looking flat cap. They are so well known for failing randomly. I’ve been through 5 in 5 years. They are terrible.

              Comment


              • #8
                So here is what I have done. New cap, rotor, spark plug wires, fuel filter/separator. The cap and rotor looked pretty corroded so I was really hopeful that was it, but I took it out tonight and it ran the same. I also checked fuel pressure and it was 59 psi with the pumps running. I took the fuel regulator out and it was still clean. It did loose a little pressure during the test procedure, but while running, it was where it was supposed to be. I still have the one with the filter/screen on it. I have not replaced it with the e-clip so I don't know if that is causing my issue, but I would not think so...although I know there is a service bulletin about it. I also checked compression per the manual (engine warm) and got: 125, 135, 130, 135, 130, 125, 135, 132 so they were all well within the spec of 25% from highest to lowest. The motor only has 30 hours on the rebuild.

                Something I noticed tonight is that once I got the engine to max RPM (~4300), I could pull back the throttle and the motor would not really slow down any. in fact, I could pull it back quite a bit and the motor would still run the same. I recorded the engine again using scanner pro and I am attaching the file (zipped as the site wouldn't let me upload an .xdl file), but I made a couple of screen shots that show RPM vs. throttle position and RPM vs. fuel flow. It looks like I can take the throttle all the way down to about 60% before the motor starts to slow down any from full throttle. It is like the top 30%-40% of my throttle is basically useless or not being used. I think the snip of the graphs show this really well.

                What is the next thing I need to do or check? Send my injectors out to be cleaned and tested? Thanks again for the help so far. I hope I can get this figured out.
                Attached Files

                Comment


                • #9
                  I don't know how spark advance is set on these motors (base timing, etc) but its something that will cause low power if it was done incorrectly. The ignition module will make everything run smoothly and so it seems invisible up to the point where you are needing max power and it seems like this is it. From messing around with stuff if you ever encounter a load on the engine, there's kind of a few second bog and then suddenly it feels like you have turbo boost, that's a symptom of having insufficient spark advance on the base timing.

                  A corollary is that if the engine is sensing knock it will pull spark advance back (ECM purposefully causing retard) until it doesn't find that condition any more. The ESC sensor could be giving you a false signal (was it put in the correct place, was it put in without teflon tape which could compromise the sensor's ground) are a couple things to check. There could be one ESC/knock sensor for each bank of the V8, I'm not sure how VP rolls with this.

                  Comment


                  • #10
                    125, 135, 130, 135, 130, 125, 135, 132

                    The motor only has 30 hours on the rebuild.
                    Your compression numbers indicate that the motor will run, but for a fresh rebuild, the numbers should be closer to 150. The old manuals use to list at 150 number, and later they started listing 100, the 100 is minimum needed to run. If I didn't know you had a fresh motor I would be seeing a tired motor.

                    When doing compression test is the throttle at WOT, motor is warm, there is at least 4 compression cycles per cylinder?
                    Do you know if the gauge is accurate?

                    If numbers are correct, then suggest a leak down test?

                    Your fuel pressure looks good

                    How do the plugs look?

                    This TPS is moving but not slowing the has me wonder if the ECM has been reflashed, or does not have the correct program
                    94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
                    95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
                    07 Seadoo GTX
                    Merc Adults Only VP Adults Only
                    G-Dad always said "First Liar doesn't stand a chance"

                    Comment


                    • #11
                      Originally posted by AllDodge View Post

                      Your compression numbers indicate that the motor will run, but for a fresh rebuild, the numbers should be closer to 150. The old manuals use to list at 150 number, and later they started listing 100, the 100 is minimum needed to run. If I didn't know you had a fresh motor I would be seeing a tired motor.

                      When doing compression test is the throttle at WOT, motor is warm, there is at least 4 compression cycles per cylinder?
                      Do you know if the gauge is accurate?

                      If numbers are correct, then suggest a leak down test?

                      Your fuel pressure looks good

                      How do the plugs look?

                      This TPS is moving but not slowing the has me wonder if the ECM has been reflashed, or does not have the correct program
                      I was thinking that the pressures were a little low myself, so I checked the guage against my air compressor that has 2 gauges on it and the compression tester read about 35 pounds low. I returned it and got another one and checked it with the compressor and the new guage read about 10 pounds low, but much closer than the old one. I checked 2 of the easiest cylinders to reach and the first one with the old guage I got 125 and the new one gave 146. The second one that was 135 is now 151 so my original guage was definitely reading at least 25-35 pounds low based on the reference gauge. I did do both tests with the motor hot, but I did forget to open the throttle on the one I did tonight, it was wide open on the test the other day. So my numbers tonight might have been a little higher if I had remembered to open the throttle.

                      The plugs looked good to me. I am attaching a couple of pictures. They only have about 30 hours on them. I regapped them before reinstalling just to be sure.

                      I purchased the complete engine that had been rebuilt...after getting hydrolocked I think they said...so I don't know the entire history of the motor and, based on the results I saw of the rebuild, nothing would surprise me, but i am assuming that the ECM is original and hasn't been messed with.

                      Comment


                      • #12
                        Compression is good so we rule that out
                        Plugs look like your running rich and might account for why you can pickup speed while bringing the throttle back. Its so rich that bringing the throttle back at speed leans out the mix

                        If there is no vacuum leak, then might be time to test the injectors
                        94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
                        95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
                        07 Seadoo GTX
                        Merc Adults Only VP Adults Only
                        G-Dad always said "First Liar doesn't stand a chance"

                        Comment


                        • #13
                          Just wondering before I take off the injectors and send them out, would the screen on the fuel regulator be causing this? I have not done the recall/TSB and I read a post that the E-clip improved their power. I tried to take the filter off, but it was attached really well and I didn't want to break it. It was definitely clean as I could see through it.

                          Comment


                          • #14
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                            Originally posted by lonewolf41 View Post
                            Just wondering before I take off the injectors and send them out, would the screen on the fuel regulator be causing this? I have not done the recall/TSB and I read a post that the E-clip improved their power. I tried to take the filter off, but it was attached really well and I didn't want to break it. It was definitely clean as I could see through it.
                            Unable to say with 100% accuracy (maybe muc or Fun Times can) but your pressure is good. according to the specs I have. You have wet plugs so there are at least 2 which are getting to much fuel. The regulator regulats pressure and appears to be working.

                            In short I'm out of ideas other then the possibilities of injector issues
                            If you do send them out, do find a marine injector place with a good rep. Many say they can clean and flow test, but they need to flow test up to 6000 rpm. Also do have the baskets replaced which normally is included in the process
                            94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
                            95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
                            07 Seadoo GTX
                            Merc Adults Only VP Adults Only
                            G-Dad always said "First Liar doesn't stand a chance"

                            Comment

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