Thread: Vmax surging

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  1. Member
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    #21
    Took the boat for the first time since hibernation. Haven’t taken the carbs apart or anything til I seen how it ran after I replaced a small fuel line hose goin from filter to lower pump, what was on there before wasn’t right. Threw a can of sea foam in the gas tank that less than a 1/4 full.

    Unfortunately I seem to have the same issue running it. Most of the time it doesn’t even get to full rpm, instead gets up to about the 4300-4700 rpm range and top end speed around 40-45 mph. Sometimes it will open up initially when I dump it but cuts back to aforementioned speeds. Guess I’m goin to have to set a day aside to pull the carbs off.

    Im pretty sure this seems like a problem in fuel system somewhere and hopefully nothing else. Got new fuel line coming from tank without the anti siphon valve all the way to a new bulb. Replaced water/fuel separator, fuel pumps, plugs. Didn’t replace the fuel filter itself as the one in it seemed good to me, I do have a new one on hand though.

    Other than the WOT issue it seems to be running good although my brother said when he launched me and I went to go pick him up on shore, he thought that the engine seems like it was kinda surging or missing or something when I was just idling and running slow. I don’t notice much behind the wheel with my ears.

  2. Member cwilt's Avatar
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    #22
    Reeds were not that bad. The oil lines going to the carbs were fun, them little clips were a pain. Take pics with your phone so you remember the routing, especially the vacuum lines on the intake block on the starboard side. I numbered them with a magic marker. All said, it was pretty easy but I am a mechanic by trade. Before diving in did you make sure all plugs are firing?
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    #23
    Quote Originally Posted by cwilt View Post
    Reeds were not that bad. The oil lines going to the carbs were fun, them little clips were a pain. Take pics with your phone so you remember the routing, especially the vacuum lines on the intake block on the starboard side. I numbered them with a magic marker. All said, it was pretty easy but I am a mechanic by trade. Before diving in did you make sure all plugs are firing?
    Thank you for the feedback! I wondered if it could possibly be something like a bad coil pack causing this issue. It seems when it does open up and dies off the engine never regains speed or rpm.

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    #24
    So I'm goin to be pulling the carbs this weekend. Just been very busy lately. One thing I forgot to mention is when my boat is stored away and my motor is trimmed up and I take the cowling cover off, I noticed a little bit of gas coming from top carburetor. You can see maybe about an ounce of gas puddled up inside engine. Is this normal? Or is it a possibility I have a leaky gasket that would be causing my jigh speed surging issue?

  5. Member cwilt's Avatar
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    #25
    Quote Originally Posted by bigfoot17 View Post
    So I'm goin to be pulling the carbs this weekend. Just been very busy lately. One thing I forgot to mention is when my boat is stored away and my motor is trimmed up and I take the cowling cover off, I noticed a little bit of gas coming from top carburetor. You can see maybe about an ounce of gas puddled up inside engine. Is this normal? Or is it a possibility I have a leaky gasket that would be causing my jigh speed surging issue?
    That is a possibility, if fuel is leaking out, air can definitely leak in. Causing a lean condition. Can you see where it's leaking from? I have see oil leak from the carbs when tilted fed.
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    #26
    I thought about buying 3 rebuild kits just for piece of mind but don't know if I really need to go that route with a 14 year old engine that doesn't have a ton of hours on it.

  7. Member cwilt's Avatar
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    #27
    Quote Originally Posted by bigfoot17 View Post
    I thought about buying 3 rebuild kits just for piece of mind but don't know if I really need to go that route with a 14 year old engine that doesn't have a ton of hours on it.
    I rebuilt all three at around 10 years of service (dont remember exactly). My thoughts were if I was taking one carb off, might as well do all three. Thats also when i put chris carsons reeds in. I am not about taking it apart numerous times. If you truly want to make your motor reliable, then all three need to be rebuilt to put your potential fuel delivery issue to rest.
    2008 Ranger 178VX
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    #28
    Quote Originally Posted by cwilt View Post
    I rebuilt all three at around 10 years of service (dont remember exactly). My thoughts were if I was taking one carb off, might as well do all three. Thats also when i put chris carsons reeds in. I am not about taking it apart numerous times. If you truly want to make your motor reliable, then all three need to be rebuilt to put your potential fuel delivery issue to rest.
    When you went to go rebuild them was there any components that looked like they needed replacing?

  9. Member cwilt's Avatar
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    #29
    Quote Originally Posted by bigfoot17 View Post
    When you went to go rebuild them was there any components that looked like they needed replacing?
    I dont think so...I rebuilt my carbs because I had a rough idle.
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    #30
    So I pulled the carbs and gave them a thorough cleaning today. Here’s the things I found.

    1. The metal part of one of the floats was a little distorted and was a bit detached from the plastic float itself. As much as I tried to bend the tab around I couldn’t get the float to start pulling the needle immediately when floating up. Had to adjust a couple other floats with the height too.

    2. I found a handful or more of little pieces of what kinda looked deteriorated fuel line or something in the middle carb bowl. Small little clear brownish colored plastic or something.

    3. Missing one gasket (washer) for one plug on top the carburetor bowl.

    Not related to the carbs but missing three screws in the air intake silencer too.

    Needless to say I have a few items on order. Not sure if these things are the cause of my problems.

  11. Member cwilt's Avatar
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    #31
    Quote Originally Posted by bigfoot17 View Post
    So I pulled the carbs and gave them a thorough cleaning today. Here’s the things I found.

    1. The metal part of one of the floats was a little distorted and was a bit detached from the plastic float itself. As much as I tried to bend the tab around I couldn’t get the float to start pulling the needle immediately when floating up. Had to adjust a couple other floats with the height too.

    2. I found a handful or more of little pieces of what kinda looked deteriorated fuel line or something in the middle carb bowl. Small little clear brownish colored plastic or something.

    3. Missing one gasket (washer) for one plug on top the carburetor bowl.

    Not related to the carbs but missing three screws in the air intake silencer too.

    Needless to say I have a few items on order. Not sure if these things are the cause of my problems.
    The float issue can definitely cause your problems. They supply metered fuel via the needle valves to the motor. Missing gaskets is also a problem that needs to be addressed. That can introduce air into the engine fuel feed system, causing a lean condition. If them little pieces of rotted fuel line get caught up in your high speed jets, you got major problems. I would look really hard at the little rubber fuel lines connected to the carbs.
    2008 Ranger 178VX
    150 Yamaha V-max

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    #32
    Quote Originally Posted by cwilt View Post
    The float issue can definitely cause your problems. They supply metered fuel via the needle valves to the motor. Missing gaskets is also a problem that needs to be addressed. That can introduce air into the engine fuel feed system, causing a lean condition. If them little pieces of rotted fuel line get caught up in your high speed jets, you got major problems. I would look really hard at the little rubber fuel lines connected to the carbs.
    This is where I’m not knowledgeable, so I have maybe a dumb question. Are there high speed jets in every carburetor assembly or are the in one particular assembly (top/middle/bottom)?

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    #33
    Quote Originally Posted by bigfoot17 View Post
    This is where I’m not knowledgeable, so I have maybe a dumb question. Are there high speed jets in every carburetor assembly or are the in one particular assembly (top/middle/bottom)?
    Each carb (setup as double barrel) has a single float and distributes the fuel to one cylinder via a low speed and high speed jet. Each cylinder gets the treat of lesser or greater fuel and consequently, oil mixed in.... There's a reason you need to do a lync and sync on carbed models like ours... :D I ordered all three rebuild kits, tried to take my time and make sure each carb, low speed jet and high speed jet was clear... It certainly helped on our 99 P200 TLRX... Well, so did the reeds and stuffer plates...

    Well written Lync and sync post....
    http://www.bbcboards.net/showthread.php?t=826681

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    #34
    I did take a look at the reeds and they seemed to be fine.

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    #35
    Put the carbs back on today after I cleaned them and replace a few parts. Still have the same issue. I’m about to look at timing and coil packs.

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    #36
    Quote Originally Posted by bigfoot17 View Post
    Put the carbs back on today after I cleaned them and replace a few parts. Still have the same issue. I’m about to look at timing and coil packs.
    I did buy aftermarket coils as well, when I was trying to diagnose my P200 TLRX issues. While I found out that was not the cause, you can check the resistance on the individual coils. Also a good idea to try a spark tester first. A cheap diagnostic tool at any decent auto parts place. Since the coils are high voltage, but not like super high, you should be able to see a blue spark in the tester when you crank the starter. I did this with all plugs out. Some suggest not to. I can't remember if you said you did a compression check or not? A good time to do that while in the process..... Good luck man... I know the frustration, seriously...

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    #37
    When I took the boat out yesterday I had her almost seeming to want to open up. Got it up to 50-51mph and about 5200 rpm but you can still hear and feel like it’s missing or surging. Then another short little run I did, which was actually my first one I couldn’t get passed 4400 rpm and about 39 mph. Almost as if it has a fuel delivery problem but I’m not sure anymore.
    I did perform a compression test a while back and all 6 cylinders checked out fine. Also I did a resistance check on the spark plug caps themselves but have not done a spark test yet which I do have the tool.

    Now think I’m goin to replace the fuel line that comes from the primer bulb to the fuel filter on the engine, it’s the only piece of fuel line I have not replaced besides the little gray ones that go to the carbs but they look good from what I can see. I noticed this particular fuel line ISN’T the original that comes with vmax engines went first bought brand new. It’s a 5/16” ID black fuel line that’s on there now. The proper one on Crowley marine is 45 bucks which I don’t mind spending if I knew that was the issue. I will say the line I’m talking about feels a little soft, wondering if it’s collapsing under high pressure?

    The coil packs are on my mind now and I’m not sure if this would affect my condition but is there a possibility that timing and/or throttle cable positioning could causing a surging issue at WOT?

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    #38
    Timing certainly could.... If you do that link and sync sequence, it should get the advance arm in the right position anyway... As far as the coils, also a distinct possibility if limited spark, or not enough spark at higher RPMs. One trick I have used since spark plugs are cheap.... Put a new set in (or decently clean the older ones), run it for a bit, then pull them after your run, keep ing track of which cylinder... . You should see evidence of proper detonation on each plug. If there is a fuel starvation issue, there won't be as much initial carbon.... Similarly, if the spark supplied by the coil isn't sufficient, it will be extremely wet/coated with fuel mix.... and lack of detonation... It might help narrow down if it is an individual coil/plug or whatever... Then you can swap coils to further isolate...

    The Position sensor on the top near the flywheel, would probably cause issues throughout the entire RPM range. Honestly not sure about that though. I replaced all of my fuel lines as well... From the water separator filter, to the motor and from the on board filter to the low pressure pumps... I used decent quality fuel line available at O'Reilles though... I am a firm believer there are many marine products that are way overpriced, due to the label they have on them... :D

    Based on all the crap you found in the carbs.... I wouldn't be surprised if something is still partially clogged... I have run into this since getting my P200. As a matter of fact, I just did the total carb chem dip/clean deal yesterday https://www.amazon.com/Berryman-Prod...06612359&psc=1 to the top and bottom carb sets.... I let them soak, then use compressed air to blow out the various ports etc... Even a slight amount of water in the fuel can cause the jets to clog or partially clog, which could limit fuel delivery to an individual cylinder through the high speed jet(s).

    Good luck man!
    Last edited by Smallie_Hawgin; 04-27-2022 at 11:51 AM.

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    #39
    Another idea, hit the choke (assuming this is electronically activated by the key push like mine is) when it's doing the low end of the surge... If it instantly gets better, then you know you are starving a cylinder, or cylinders of fuel. I am still having a problem with the mid range jets. Stumbles a bit on take off, unless I do the choke trick I mentioned, then she revs up quickly as it's supposed to...

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    #40
    Quote Originally Posted by Smallie_Hawgin View Post
    Another idea, hit the choke (assuming this is electronically activated by the key push like mine is) when it's doing the low end of the surge... If it instantly gets better, then you know you are starving a cylinder, or cylinders of fuel. I am still having a problem with the mid range jets. Stumbles a bit on take off, unless I do the choke trick I mentioned, then she revs up quickly as it's supposed to...
    I believe I tried that trick a couple times without any difference. I just push the key in while it's running but still seems the same.

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