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06 f225 TXR

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  • #16
    Originally posted by OneStepSally View Post
    Wouldn't pumping the ball force fuel into the vst? I can pump it a few times and it gets really hard but the engine does not react at all.
    well then you need to monitor the rail pressure while all of this is going on.
    if the pressure still drops while you are pumping the bulb then look for for something different

    you could monitor the lift pump pressure and vacuum also to see what that is all doing
    Last edited by 99yam40; 07-11-2020, 05:29 PM.

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    • #17
      What should the lift pump pressure be?

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      • #18
        In post #10 you said the engine ran great on the portable tank and when switched back to the boat tank it acted up again, then went back to portable tank and engine ran properly again.
        This tells me that it is the boats fuel system that is causing the problem OR the lift pump is getting weak or sucking air from somewhere on the boat side.

        Perhaps when the portable tank is connected the pump can keep up but when you add the extra hose lenght and internal tank pickup...it can't. Or the pump maybe fine and sucking air.

        You can plumb in a piece of clear fuel hose after the lift pump and look for bubbles when connected to the boats fuel tank. Try and SEE what is happening.

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        • #19
          Finally got to run the boat today with the clear line on the pressure side of the LP pump. I installed it between the vst and the "F" filter sling with a tee/Schrader to check the pressure of it. What I have learned is this:

          1) For the first 10 minutes of run time the engine ran perfect. The LP pump was not cycling off like it should under 1200rpm, but there are no bubbles from any vacuum side leaks.

          2) After about 10 minutes of running it hard we dropped back to idle to talk about it (my dad was with me today) and the LP pump started to cycle (10 sec on, 20 sec off). We noticed that every time the pump cycled off we would get air in the line from the fuel siphoning back so it seemed. After this started it immediately started running poorly. The air would clear as soon as the pump cycled back on but we watched it do this for 5 or 6 cycles. The timing of the cycle was correct and we had 11-12 psi at all times while the pump was running.

          3) After 5 minutes of poor running we shut the engine down and I pushed the Schrader down that is behind the rubber thing on the top of the vst tank (part #37) thinking maybe there was a vapor lock on it. I got nothing, no air, no fuel. Tried again with the engine at idle and same results. The engine did seem to run better after but I'm not sure that did anything or not.

          4) After that point we ran more and it actually started running great again, but at some point the pump stopped cycling again. We were starting to lose light by this point so we decided to go back to shore. We did a lot of idling back to the ramp so we could talk about what we had seen and 100 yards from shore the pump started cycling again. This time there was no sign of fuel feeding back, so we turned around and took off again. It still ran great. While waiting on my turn for the ramp I removed the gauge from the LP line and it created a few bubbles so I turned and took off to see and it had a mild case of the bogging but it cleared up after a few seconds.

          So all that for this.....

          After getting home I did find a cracked hose on the vent off the top of the vst tank (picture right side of piece #23). Could that be the cause of the fuel draining back?

          Check valves could cause it but don't they normally fail completely and not intermittently?

          Why is my LP pump cycling some of the time but not always?

          What should I check next? I will be fixing the cracked hose but since it's on the vent side I wouldn't think it'd be the problem. Hopefully it is so I cam put this to bed.

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          • #20
            if the LP pump is not cycling ,is it running all of the time or not running at all?

            I would think the vent on top of VST is there to give the air in VST somewhere to go as it fills up.
            should have an orfice in there maybe, not a check valve

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            • #21
              Originally posted by 99yam40 View Post
              if the LP pump is not cycling ,is it running all of the time or not running at all?

              I would think the vent on top of VST is there to give the air in VST somewhere to go as it fills up.
              should have an orifice in there maybe, not a check valve
              It is running all the time when it's not cycling like it should. Also to note that it is consistently running at 11-12 psi when it is running.

              There is an orifice, it's part #25 in the picture. It was stopped up but I was able to clear it earlier in the troubleshooting of this problem. There is also a check valve lower in the vent system going toward the canister, I think it's part #40. It was good when I checked it. I will try to get the cracked vent hose fixed tonight and see if I am getting any air when the LP pump cycles off. To check if it causes any issue I'm going to run it on the trailer with the vent line removed and open to atmosphere. If I do and it goes away once replaced I will know that it was the culprit letting the air behind enemy lines LOL.

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              • #22
                I have repaired the little vent hose that was cracked (pictured #1). I'm still getting air (fuel draining back), after a few minutes of the engine being off I get what's in picture #2. When the pump cycles off I get a dozen tiny bubbles that collect into 1 bigger (but still small) bubble at the high spot in my line (picture #3). The first time I saw this was on the lake and half of the clear line drained back when the pump cycled off. I'm not sure what is stopping it from going more now or was causing it to go as far before.

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                • #23
                  So the motor is running as bad as it ever has. Ran it yesterday and for the first 10 minutes I was only able to finagle 5200 rpm out if it, but the longer it ran the worse it got. By the 30 minute mark I could only get 2800-3000 rpm. Priming the ball while running changes nothing. I don't think I'm getting any air on the suction side of the LP pump because when the LP pump is running there are no bubbles and the pressure is steady at 11psi. Rail pressure is what is causing the problem. I'm getting the 44psi with the key on. It drops to 38psi when cranked and idling. Upon acceleration when cold the pressure starts to go up but falls after reaching half throttle. It makes it to 42psi but beyond half throttle it drops to 25psi or so. The hotter the engine gets the further and faster it seems to drop. Based on this my questions are this:

                  1) Does the HP pump run at a constant speed or does the engine speed the pump to meet demand?

                  2) If the pump speed is con*****ed what gives the signal? TPS?

                  3) Is it common for a pump like this to get weak and not supply enough fuel especially once it's hot. (I'm in central Florida so the air temp is in the mid 90's with the water temp nearly 90 as well)

                  At this point I'm leaning toward the HP pump not supplying adequate fuel to the rail and once it gets hot it supplies even less. This would also explain why it seemed to be a gradual problem when it first started.

                  To date I've done everything below:

                  1) Replaced the spin on filter.
                  2) Replaced the small filter under the intake plenum.
                  3) Replaced the "F" filter.
                  4) Replaced the VST screen.
                  5) Checked all the check valves.
                  6) Inspected and repaired any and all lines under the hood.
                  7) Replaced all fuel lines from the tank to the engine.
                  8) Checked tank vent lines.
                  9) Checked LP pump pressure (11-12 psi).

                  I'd be open for a phone conversation if it's easier. I'm to the point that it's about to go to a shop or the sand at the bottom of the lake LOL.

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                  • #24
                    Originally posted by OneStepSally View Post
                    beyond half throttle it drops to 25psi or so.
                    1) Does the HP pump run at a constant speed or does the engine speed the pump to meet demand?

                    2) If the pump speed is con*****ed what gives the signal? TPS?

                    3) Is it common for a pump like this to get weak and not supply enough fuel especially once it's hot. (I'm in central Florida so the air temp is in the mid 90's with the water temp nearly 90 as well)
                    Good work getting the rail pressure data!

                    The pump is simply on or off - clearly it is running when it should.

                    Possible effect of temperature?
                    well, 'vapor lock' is when fuel 'boils' - changes from a liquid to a gas -
                    and of course that gets more likely as the temperature increases.

                    Personally though I'm fixated on "Priming the ball while running changes nothing."

                    IMO, from the 'feel' of the bulb, it should be possible to confirm if the VST is full - or not.

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                    • #25
                      Originally posted by fairdeal View Post

                      The pump is simply on or off - clearly it is running when it should

                      IMO, from the 'feel' of the bulb, it should be possible to confirm if the VST is full - or not.
                      That's what I was afraid of on the state of the pump.

                      Bulb is slightly soft when I squeeze it but it's hard within about 4 or 5 squeezes.

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                      • #26
                        4-5 squeezes after running is ALOT..

                        On my F150, if I can get one squeeze is a bunch (after running).
                        If the engine sits for say a month, 1.5 squeezes tops fills up and is hard..
                        Scott
                        1997 Angler 204, Center Console powered by a 2006 Yamaha F150TXR

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                        • #27
                          drain the VST and then see how many pumps of the bulb it takes to fill it up.

                          some bulbs are bigger than others,
                          and it also depends on how flat you squeeze the bulb each time
                          Last edited by 99yam40; 08-10-2020, 09:08 AM.

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                          • #28
                            Is there any way to drain it without pulling it off?

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                            • #29
                              fairdeal should be able to answer that for you

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                              • #30
                                Originally posted by OneStepSally View Post
                                Is there any way to drain it without pulling it off?
                                Part #7 is the drain plug: https://www.boats.net/catalog/yamaha...jection-pump-1

                                Dunno how hard it is to get to it...

                                Capture.JPG
                                Scott
                                1997 Angler 204, Center Console powered by a 2006 Yamaha F150TXR

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