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4.3 GL starving for fuel

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  • 4.3 GL starving for fuel

    My fuel system seems to be intermittently starving for fuel. I can start it easily but after cruising for 30-40 minutes, it just dies. Checked filter water seperate an it's clean wit no water. Yesterday we were out and it happened agsin. I unscrewed filter and it seemed like barely any fuel in filter. Spun it back on, cranked up and went maybe 100 yards and stalled again and couldn't get it started and got towed back to house which fortunately was only about half mile away. This morning it cranked right up without even pumping throttle so I took it for a short spin but scared to venture out again with passengers until I can figure this one out. Gast tank vent was free and anti-siphon line seems to be okay. I and my family are at our wits end and they won't get back in boat. Any suggestions? The boat is a 1995 model but reman jasper put in several years ago and only had about 70 hours on it.
    1995 Chris Craft Concept 18, 4.3 VMC7, VP outdrive

  • #2
    Mechanical or electric fuel pump?

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    • #3
      When you start the motor and its running listen for the fuel pump, is it running?
      Take a voltmeter and check for power at the pump?

      If it is running and you have power to the pump, then need to check fuel pressure at the carb. To check pressure you will need a vacuum fuel pump tester or borrow one

      https://www.harborfreight.com/fuel-p...ter-62637.html

      Need to place this gauge between the pump and carb. Can find some fittings at an auto store. If your unfalimar with these fittings, remove the hard steel fuel line and take it to the store. Get some rubber fuel line, fuel pump and carb barbed fittings, and a Tee fitting, along with some hose clamps.

      Once testing is done, put your fuel line back on

      Click image for larger version

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      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"

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      • #4
        Jimmbo, how do I know which one I have?
        1995 Chris Craft Concept 18, 4.3 VMC7, VP outdrive

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        • #5
          Thanks for the reply alldodge. Unfortunately I'm quite a ways from anywhere that has these items and most of my good tools are at the house. I'm just confused as to why the motor runs fine sometimes for hours and other times I experience no fuel.
          1995 Chris Craft Concept 18, 4.3 VMC7, VP outdrive

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          • #6
            I'm at a loss also unless were able to test something. One time you can run 30-40 and it dies and fuel filter is full, next time its almost empty. So unless we can figure out what is missing, like you were at a loss.

            Being a GL you should have an electric fuel pump so that is where I would start looking
            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


            • #7
              Could be a crack in a fitting somewhere before the pump, or rubber has failed somewhere, and it is losing suction. Fuel will not leak anywhere, just lets air in and fuel will not draw in. Just spitballin'.
              2002 Bryant 188 4.3MPI

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              • #8
                Originally posted by Alaboat View Post
                Jimmbo, how do I know which one I have?

                Trace the fuel line backwards from the carb, an electric pump is on the starboard side but in front of the engine and the fuel enters the bottom, and exits the top of the pump. A mechanical pump would be mounted on the side of the engine block.

                The wiring diagram shows an electric pump, but it is for a V8, as well as having electronic spark advance distributor, something that might not have been on a 1995 engine

                Comment


                • #9
                  Went out again this morning and cruised at about 30 for 10-15 minutes then idled in a no wake for about the same amount of time. Engine died again, removed screw on filter and it was less than half full. Spun it back on and got it cranked again and cruised back to dock for another 15 minutes, no problem. Removed filter again and rinsed out filter with fresh gas and no trash to speak of. Also let it idle at dock for 15 minutes and no problem. Alldodge, you asked if I could hear pump running when engine is running, no, can't hear anything but I did unplug electrical connection to pump once fuel in filter runs out, it stalls but once plugged back in, runs fine again.
                  1995 Chris Craft Concept 18, 4.3 VMC7, VP outdrive

                  Comment


                  • #10
                    With it sometime running fine for hours and sometimes not, it could be the pump, but is most likely electrical supply to the pump. You have a fuel pump relay and it may be going out or bad connection. If you can get a pressure gauge installed, it can help identify the issue(s).

                    Relays are fairly cheep
                    Take it to the local auto store and they should have one
                    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
                      Thanks, I'm going to see if I can find the pump relay and at least check connections. I just replaced starter relay recently and cheap from auto parts store.
                      1995 Chris Craft Concept 18, 4.3 VMC7, VP outdrive

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                      • #12
                        Didn't want to let this thread die or get forgotten. I like to close the loop so that others coming behind can have useful information. I did find the relay and connections looked good with no corrosion. As expected, when the relay was unplugged with engine running, it would die soon after it was unplugged. I guess there's no way to test an intermittent electrical failure (in this case, a relay) unless you catch it when it happens. I'll just replace the relay and hope that is it.
                        1995 Chris Craft Concept 18, 4.3 VMC7, VP outdrive

                        Comment


                        • #13
                          I hope it's okay to dredge up old threads on this forum so here goes. Last fall when I winterized my engine, I also installed a new fuel pump relay hoping to fix my fuel issue. I de winterized the boat this weekend and took it our for a spin. Low and behold, the same issue is still going on. Engine cranks, idles, and runs fine at low speeds but about 10 minutes into cruising at 30 MPH, engine dies. Repeated this several times so just decided to cruise around at 5 MPH for 30 minutes or so and all is well. Me thinks there is a fuel issue somewhere that is creating a vacuum on tank at higher speeds but fine at lower speeds. I did open the fill cap on tank and cruised a short time like that but didn't push it too long because I didn't feel like getting stranded again and getting towed in. Maybe coincidence that it didn't die with cap opened or do you think I'm on to something? I hate to take it to the mechanic but that's my next stop unless I can figure this out with your help.
                          1995 Chris Craft Concept 18, 4.3 VMC7, VP outdrive

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                          • #14
                            There is never an issue posting to an old thread by the thread starter. You started this one, so no issue

                            You have the same issue, but no testing has been done yet. Running the boat at 30 mph uses much more gas then at 5. Removing the gas cap at 5 is not telling much, but if you did this at 30 would be able to say something.

                            You either have a restriction or weak pump. Need a pressure gauge inline to test.

                            Remove the anti-siphon valve from top of the tank and see if it has any crud in it, and moves freely. Should be able to blow thru with mouth pressure in one direction
                            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


                            • #15
                              Sign up today
                              AllDodge, thanks for the quick responses now and previous. I plan on going our to where my boat is stored this week sometime and getting at the top of my tank under the floor and inspecting hoses and fittings. I'll pay close attention to the anti-siphon valve and ensure the vent line is clear. It's gotta be something simple. Also gonna look at condition of fuel lines. If all is well, I'll focus on the pump but don't really have the tools to test it.
                              1995 Chris Craft Concept 18, 4.3 VMC7, VP outdrive

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