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1995 Merc Blackmax Troubleshooting Problem

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  • 1995 Merc Blackmax Troubleshooting Problem

    Engine troubles of course on the maiden voyage. Let me give you some background and you can tell me what you think if you don't mind.

    1995 Mercury 3.0L Black Max 225hp with brand new powerhead and lower unit. Boat was test drove in Florida about in April and then I've had a hard time getting it up here. Compression is perfect and the boat ran 46mph on the sea trial done by the surveyor. No problems.

    I took it out for the first trip and we idled out... boat did fine.. smooth idle. Got out of the No Wake Zone and smoothly pushed the throttled down. She started to come out of the hole and on plane and at about 15 mph she completely lost power but did not quite shut off. This was about 2 to 4 seconds after putting the throttle down. It coughed a little and I backed the throttle off and then she went right back to idling smooth. I tried it again and it lost power much quicker this time never trying to get out of the hole. The bulb felt flat and my first thought was a fuel restriction of some kind. If I pumped the bulb up hard it would try to get out of the hole and die back. Well it ran just fine at 1200 rpms but if I eased up over that much it would lose power and almost shut down. Sometimes it did shut down. Ok.. now we decided to just troll for blues about 5mph or 1100 rpms. Boat did fine but if we rocked hard by a boat wake it would cough and sputter and die or possibly not die and get back to idling once the wakes passed. It seemed to need to rock pretty good to make this happen. Normal boat wakes didn't do it but a big sport fish or good swell would cause the engine to struggle and cough even at 1000rpms. So now I'm wondering could it have something to do with floats in the carbs or fuel sloshing around in the gas tank or what? It does it very soon after the boat rocks hard.

    Ok.. put it on the trailer I looked at the water sep filter and it was rusted onto the aluminum housing and the housing was completely corroded. No hope of even saving the frame of the sep filter. I bought a new Racor filter and frame and installed it along with a new section of line from the filter to the engine. New bulb and all. Bulb pumps firm very easily. Thought a check valve could be messed up in the bulb and it was a bit old. Ok... took the boat out today. Idled around fine and the boat even ran fine out of gear on a hose up to 5000 rpms. Idled around smoothly about 1200-1300 rpms casting at spanish then decided to head out to the inlet. She came up on plane almost probably reaching almost 20mph and I thought it was fixed then it suddenly died again. Then the same exact problems. Only thing that was different was that it started idling much rougher after that and then might idle smooth for a while. Rough for the next 20 minutes and then smooth for a minute or two but if you pushed the throttle much you got no response and it would lose power or shut off.

    The tank is half full and sat half full often I would imagine down there in florida. Could it be water in the fuel tank?? Do I have a water sep filter in this model engine as well? Honestly I have to look agaain to see. The sloshing is making me wonder floats, carbs, water? The boat sat too long with some bad fuel and then something about trailering it 12 hours sloshing around a half empty tank?? any ideas???

    Feel free to email me any suggestions at [email protected]

    Thanks in advance!!!
    Shacklefordcharters.com[br]Atlantic Beach, NC

  • #2
    I believe your on the right trail, it seems like a fuel issue to me.

    try putting a inline fuel pump just after the tank conection. You can wire this to the ignition ACC. conection. this will supply fuel to the engine, if you dont want to go that far yet. then try the fuel filter inside the motor compartment. There is a screen in the tank and a anti-siphon valve on some units. the elect. pump just helps the marginal engine pumps do a better job. Napa stores have them in stock. Ask for a marine version if they have one. Others will have good ideas also. dave.
    [br]1994 Mako 215 Dual console Optimax 225[br]1978 Mako 19 with 90hp johnson[br]1996 Mako 22[br]1982 Mako 171 Angler 135 Black Max Mercury[br]1987 21b 225 Yamaha[br]1974 23 inboard Gusto gone.[br]1979m21 225johnson \"blue dolphin\" bought off this board and restored [br]with everyone\'s help!!Gone but not Forgotten....[br]1979 20 Mako 115 Suzuki gone[br]1977 19 Mako 115 Johnson gone[br]1976 23 Mako twin 140 Johnsons gone[br]1983 224 with closed transom and bracket[br]And 162 SOB (some other boats)[br]Venice Florida, Traverse city Mi.

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    • #3
      tried an experiment... I had a guy pump the bulb while trying to geton plane to keep it solid. Didn't really help. Still had the problem. Does this help any?
      Shacklefordcharters.com[br]Atlantic Beach, NC

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      • #4
        Water in the fuel tank sounds like.....new gas should make the problem go away.

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        • #5
          Is it running on all 6 ? you can pull a sparkplug wire off on at a time and listen for the change in the engine running. I still think its fuel related though. If you have the ability you might consider cleaning the carbs. Might not hurt to get it checked out. dave
          [br]1994 Mako 215 Dual console Optimax 225[br]1978 Mako 19 with 90hp johnson[br]1996 Mako 22[br]1982 Mako 171 Angler 135 Black Max Mercury[br]1987 21b 225 Yamaha[br]1974 23 inboard Gusto gone.[br]1979m21 225johnson \"blue dolphin\" bought off this board and restored [br]with everyone\'s help!!Gone but not Forgotten....[br]1979 20 Mako 115 Suzuki gone[br]1977 19 Mako 115 Johnson gone[br]1976 23 Mako twin 140 Johnsons gone[br]1983 224 with closed transom and bracket[br]And 162 SOB (some other boats)[br]Venice Florida, Traverse city Mi.

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          • #6
            Try a portible tank for testing.

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            • #7
              I had the same exact problem with my 89 evinrude 225. Turns out it wasn't fireing on all 6 cylinders. I chased the fuel issue for several days. When I checked for fireing found out the entire port side was not. Tried changing the powerpack but no luck, it's beyond my ability now with very few tools so I made an appt to take it to the shop.
              Troy[br]Pensacola, FL[br]1977 21\' Mako Deep V[br]http://www.classicmako.com/forum/topic.asp?TOPIC_ID=20954

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              • #8
                Just pulled the carbs and dumped some of the gas... pumped some gas directly into a cup by squeezing the bulb. small flecks of garbage in each pump. Looks like about 3 or 4 flecks about the size of very small grains of sand. That's enough to cause some trouble I'd say... everyone agree? I'm getting a portable tank and going to see how it runs on that after I clean out the carbs and replace the inline filter. Hope this helps some. Just not sure why it runs just fine without any load up to 5000. Guess it's not pulling quite as much fuel.

                When she first takes off she runs like a champ smooth then just dies as if you dropped the throttle back and coughs terribly. I'm thinking it has to be this crappy fuel. I hope that's all there is to it. Anything else that might get clogged besides the inline fuel filter in the engine, and carbs? Should I worry about the fuel pump? The flakes in the fuel are like flakes of pepper in size.
                Shacklefordcharters.com[br]Atlantic Beach, NC

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                • #9
                  My guess is that those little flakes found their way into the high speed jets of one or more carbs. This would cause the motor to die at throttle under load but run ok at idle and under no load to a certain degree.
                  Larry S. - Fort Pierce, Florida[br]23 Contender

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                  • #10
                    OK.. here is my update. Soaked carbs for a couple hours in GUNK carb dip with all the plastic removed. Went and bought the rebuild kits and reassembled them after cleaning. They were a little dirty but not as bad as I thought. Pretty simple carbs too. Well, put it back together and new inline filter and then added a portable fuel tank to the line to rule out the intake and keep any garbage out. Well..... went to the ramp tonight and put the boat in the water but still on the trailer.

                    Cranked her up and she sounded pretty good. Let her idle a bit and then put her in gear up to about 2500 rpms really churning some water. Sounded good. About 45 seconds later she sputtered... dropped all power and really coughed. I thought she might be getting out a little trash even though there should be none now. Tried again and did the same thing. Then the period of runnin smooth dropped down to only seconds at 1500 to 2500 rpms before she'd lose power or shut off. THen I tried at idle in the water. Ran up to 3000 rpm's and let it sit at that speed out of gear. After a little while it started missing a bit and running rough. Then I simulated the boat wakes we hit the other day that caused the engine to die even at low RPM's. I grabbed the T-top post and shook myself back and forth shaking the boat pretty decent while still on the trailer. The engine tried to die immediately even at low rpms while shaking the boat but when I stopped shaking it would start idling pretty smooth again in a second or two.

                    Any chance I have some loose connection?? The skeg on this boat took a decent knock chipping it in a minor traffic accident a between the last time it was run on the water and now. Don't know if I could have a loose wire from that or what? The trash still was going to be a problem although it wasn't the smoking gun in this case.

                    On the bright side some people got a good laugh watching me shaking my boat in the dark on a public ramp up here!

                    I have some photos to attach that I had some questions about.

                    Look here and see the spot a hose looks like it should be. Assuming it should not have one since the engine ran fine when surveyed but I haven't been able to get it on the ocean for a run myself. In case you can't tell this is the starboard side by the carbs. Those 3 hoses come out and connect to the top of the carbs. There is another hose coming in the side of that little pump. This naked hose barb is coming straight out from the back.



                    This photo shows the oil reservoir and the port side of the carbs. Notice where the hose to fill the oil reservoir would normally be clamped in place. Now on the bottom of this there is an elbow with another hose barb pointing straight down. Is there supposed to be something attached here as well or is this some type of vent to let air in as the oil level dropped and prevent a vacuum? I noticed a little drop of oil hanging there at times.

                    Thanks for all the help. Tomorrow I'm going to try wiggling wires and pulling plug wires to see if I can narrow down what cylinders are giving me trouble and what the deal is. A mechanic at the dock thought it sounded like it was missing a couple cylinders. Asked about coils. WHo knows.
                    Shacklefordcharters.com[br]Atlantic Beach, NC

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                    • #11
                      Check and make sure all cylinders are firing. I had the same issue, while in neutral I could crank up the rpm's but once under load I could only get 2k. My entire port side wasn't firing. Thought it was the powerpack but I was wrong. Taking it in now. I did find the port side charging coil is bad, probably what was originally the problem.
                      Troy[br]Pensacola, FL[br]1977 21\' Mako Deep V[br]http://www.classicmako.com/forum/topic.asp?TOPIC_ID=20954

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                      • #12
                        Any ideas why shaking the boat makes the engine die?? That really bugs me. It did it time and time again.I did this about 10 times to make sure it wasn't just coincidence. [B)]
                        Shacklefordcharters.com[br]Atlantic Beach, NC

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                        • #13
                          On many outboards you can eliminate the whole boat harness and the motor will still run. This would help you to decide if there is a electrical problem or fuel problem. On my omc units I can unhook the large plug at the motor and the engine will stay running.(cant shut if off though) if you shook the boat then and still died it would be fuel.(in my opinion) this one is a tuffy. dave.
                          [br]1994 Mako 215 Dual console Optimax 225[br]1978 Mako 19 with 90hp johnson[br]1996 Mako 22[br]1982 Mako 171 Angler 135 Black Max Mercury[br]1987 21b 225 Yamaha[br]1974 23 inboard Gusto gone.[br]1979m21 225johnson \"blue dolphin\" bought off this board and restored [br]with everyone\'s help!!Gone but not Forgotten....[br]1979 20 Mako 115 Suzuki gone[br]1977 19 Mako 115 Johnson gone[br]1976 23 Mako twin 140 Johnsons gone[br]1983 224 with closed transom and bracket[br]And 162 SOB (some other boats)[br]Venice Florida, Traverse city Mi.

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                          • #14
                            OK... Have a little more information. All cylinder are sparking although some appear to be sparking "weakly" and not near as strong as the others. All of this is at idle on the hose. I put a screwdriver in the plug wires and checked for the arc to the engine block or spark plug top. I will try and show a text diagram of the results unplugging each wire had on the engine idling. I unplugged each one at a time and recorded the change. This is from top to bottom if you were looking at the back of the engine.

                            Port Cylinders

                            Moderate change

                            No change or

                            maybe very little

                            BIG change

                            Starboard Cylinders

                            No Change

                            BIG change

                            Moderate change

                            Ok.. now what do you make out of this? Also, All plug wires zap me if I unplug them at idle by hand even through the insulation except for the middle port cylinder and the top starboard cylinder wires.

                            Electrical problems are so much fun. I hope to fix this today if I can figure out where to go next.
                            Shacklefordcharters.com[br]Atlantic Beach, NC

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                            • #15
                              CaptScott,

                              Are you still running with VRO. Check your VRO output and sensor. A lot of these motors have sensors which will either not allow your engine to get to speed or will kick it back to idle if it is not getting oil or the correct amount of oil to prevent burning the mudder up. Kinda sounds like that's what's going on. Good Luck!
                              Justus[br]\'93-211 Classic [br]Baton Rouge

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