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Discussion Starter #1
Hello everyone, new kid on the block here with a running problem on my ride. Hopeful someone out there can give me some guidance. My ride is an 04 with under 12k miles. Overall it runs like a scalded dog. Here's my problem, when the tank is less than 1/2 full the bike usually will die out within 50 ft to a mile. It will only do it one time. After a few attempts starting it will fire up and I can continue on my journey home never missing a lick. I had the bike 4 years and has always had this problem. It sounds like it is starving for fuel/ran out of gas.
Here are a few facts:
1. Always happens with 1/2 or less fuel in tank.
2. Temp is always mild to hot outside.
3. After a few minutes of dieing, will usually start back up and run fine.
4. Already had the fuel tank and fuel valve apart, no issues.
5. Checked the tank vent, okay.
6. Ruled out carbs, it runs great except for the time it dies.
Ruled out electrical, the problem will only get worse if there is an issue.
7. Never fails with fuel above 1/2 full.

I feel that it's probaly something stupid but, so far I'm the one thats getting whipped here. Whatever the problem is I would think it would only get worse, wrong. It won't stay broken long enough for me to find the problem.
So my friends out there, I'm all open for suggestions and would be really grateful for any input. Thanks!
 

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Sounds a lot like POOGS. You say the tank vent is okay? Did you spray cleaner or compressed air down it and have it come from under the bike and did you clean the vent holes on the gas cap its self? There are holes on the under side of the cap that need to be cleared as well. Some have had to take the cap apart but I was successful just by spraying carb cleaner in each hole using the red spray tube. Try that and if you don't get cleaner spraying out you will have to take the cap apart. Be careful though, the cleaner can spray out of the opposite hole you are spraying in and get you in the eyes. Hold the cap facing away when you spray each hole. Hope this helps.
 

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Welcome. POOGS = Phantom Out Of Gas Syndrome. So common we came up with an acronym!
 

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^ Yep sounds like the POOGS, but there is one more simuliar problem that I had out of my 06...
You don't say where you are, but my bike was bought new in Tenn., but was a California bike with their polution stuff on it, which is legal for Kaw. to sell in other states...
I don't know what it was doin exactly, but it was causing the bike to stall after a short stop in warm weather, dang near got me run over a time or three... Anyway if it is a Cal. bike it will have 2 small lines coming off the rear of the tank, the one on the right goes to the Cal. stuff and the one on the left is the tank vent...(non Cal. Bikes only have the 1 vent line)
I think all you have to do if that is the case is pull the tube off the one on the right (to the Cal. polution stuff) and put a sheet metal screw in the metal tube tank stem... I put epoxy on the screw I put in...
Just another thought, probably is the POOGS, but if not it could be the Cal. polution control bit...
Have a good one...Old Dog...
 

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POOGS ... hehe ... I never heard of it, lol. It does make sense though. I guess you could test for the POOGS by opening the tank just above half a tank and listening for suction. Plus, If you do that, and the bike doesn't die any more, you can pretty much confirm a case of the POOGS ! The vent in the gas cap is very small, and could easily get clogged. POOGS ... that cracks me up. :)
 

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Yep, sounds like Phantom Out Of Gas Syndrome...(I coined the phrase, these guys came up with the "POOGS" thing...lol)

There is a thread here somewhere about doing a fix to the gas cap...where you enlarge the vent hole or something.

The only other suggestion is to keep a spare key in the gas cap, so while riding you can flip it open if the bike begins to sputter.

This always seems to happen just before you hit reserve, and seems to effect all model years, even though many never report a problem.

My theory on this is there is some weird point where several key things seem to work together and cause the bike to starve for fuel. Always just under a half a tank, the bike is either hot or has been sitting in the sun on a hot day, and best I can tell...the petcock is always on run...not reserve.

Many think they are going to reserve and try to switch over by flipping the lever forward only to find it does not do the trick and the bike dies anyway.

I wish I could document if anyone experiances POOGS who always keep their petcock turned to "reserve". (There is fuel gauge , the reserve setting seems redundant to many)

I sold my bike before I could test this...I had planned to remove both fuel tubes off the inside of the petcock and cut them down....to see if the POOGS showed up with a different amount of fuel in the tank.

The only other option I know of is to just always keep your tank full by topping it off when you get the chance.

KM
 

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Personally, I think it may be like a hummingbird feeder effect.
Synapse: If the bike sits in the summer sun, pressure builds in the tank. The vent relieves this pressure to atmosphere. Maybe the vent tube also works to prevent vacuum in the top portion of the tank.
Lets say the vent tube is partially blocked. When the rider begins his ride, fuel is removed from the tank through gravity feed to the carbs. As the fuel leaves the tank, pressure is reduced. There may also be a cooling effect on the tank as it moves through the air, further reducing pressure in the tank. I would think that at some point, the pressure may be reduced to vacuum. At some point after that, there may be just enough vacuum in the tank that gravity can no longer pull the fuel through the lines. Fuel flow slows, maybe starving the carbs. After the engine dies or the tank is opened to check for fuel, air is allowed to enter either through the carbs for a “burp” or the upper portion of the tank is restored to atmosphere respectfully. Just a thought.

Good luck with the fix :).
 

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Giggity!
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I had the same poogs attack my scoot. My problem ended up being in the gas cap portion of the venting. I ended up removing the gasket material (Way loose anyway) inside the gas cap & that deffinitly freed up the vent. Haven't had an issue since. But like you I thought I had a major problem. Damb POOGS! lol
 

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If it is POOGS (and it sounds like it) then it will not go away until the gas cap vent and vent line have been cleaned and are venting the gas tank properly. POOGS is nothing more than a failed gas tank venting system; either clogged or failed check valves. The process or cleaning them only takes 15 minutes and a yearly spray of carb cleaner down the vent tube should keep it from happening ever again (no enlarging of holes, spare keys, keeping gas tank above 1/2 full, etc. needed). Below is my writeup on how I solved my POOGS problem. I wish we could get this added to the Verses, along with the steps for cleaning a CA model gas cap vent.

I just went through this on my ’06 (non-CA model), exact same situation too (stall at ½ tank gas). Try this (again '06 non-CA model, other models and CA emissions may differ):

Step 1: Clean the gas cap vent tube:

  1. Place a piece of paper in front of the REAR tire
  2. Open the gas cap
  3. Spray carb cleaner into the vent tube located on the tank, near the base of the gas cap hinge. Use the straw attachment for the spray can.
  4. Observe the drips onto the piece of paper. Continue spraying until it runs clear.
  5. See UPDATE 5/5/2010 below for root cause of this particular POOGS
Step 2: Clean the gas cap vent mechanism

  1. Open the gas cap and remove the key.
  2. Cover the tank inlet tube with a rag, tape or a piece of paper to prevent dropping parts in the tank. I used a large PostIt note, which worked well.
  3. Remove the two brass screws that hold the latch mechanism on the bottom of the gas cap.
  4. Remove the latch mechanism. Note: there is a loose component in the base that covers the latch spring. Be careful not to drop it into the tank or on the floor during removal.
  5. Inspect the latch, clean as necessary (chances are this is NOT where the problem is), then set aside.
  6. Careful not to loose the 5 small springs mounted on posts under the latch mechanism. You can leave them where they are or remove them for safe keeping.
  7. Before proceeding remove the small collar from the male latch connector (look for the round key cylinder). The collar acts like a bearing when opening and closing the latch using the key. It is loose and easily lost. Slip it off and put it aside for safe keeping.
  8. Remove the two short screws at the base of the gas cap vent, but DO NOT yank the vent off yet.
  9. The vent gasket is glued to the cap (at least it was on mine) and the vent assembly might be stuck to the gasket. GENTLY, wiggle the vent back and forth to loosen it and prevent damage to the gasket.
  10. With the vent assembly removed, inspect the gasket for tears or bulges. You should see the outline of the venting path depressed into the gasket (this is normal). Spray with carb cleaner (just a little) and gently wipe with a clean cloth. Inspect the cloth for signs of debris.
  11. Now for the root of the problem; Remove the small round plastic check valve/liquid separator located on the underside of the vent assembly. GENTLY ply it out (needle nose pliers works well), careful not to damage the silicone valve covering the base of the check valve. Remove the gasket as well and place it aside. Inspect and clean the check valve, ESPECIALLY the tiny 90 degree elbow which leads to the vent hole. NOTE: there is another silicone valve cover permanently mounted in the gas cap vent itself (part of the pressure release part of the valve). DO NOT attempt to remove it or you will damage it. Just make sure it is clean and functioning.
  12. Now check the vent hole. This is where you are most likely to find the problem.
  13. Hold the vent assembly up to the light and look up from where the plastic check valve was mounted. See any light where that tiny 90 degree elbow fits? Follow the vent channels on the opposite side of the vent assembly. Any blockage?
  14. Unplug the holes and clean the venting channels.
  15. Reassemble.
Step 3: Repeat Step 1 frequently (at least once a year) to prevent this from happening again. AND/OR relocate the vent line as outlined in the UPDATE below.

UPDATE 5/5/2010: My Phantom has been uncloaked! I took a closer look at where/how the rubber vent tube exits in front of the rear tire. I found that the tube had been (and still is) rubbing against the rear tire. The 'black fluffy carbon' blocking my vent was probably rubber shavings caused by the vent tube rubbing against the tire. I've temporarily rerouted the vent tube to exit along side the coolant overflow tube to eliminate the vent tube/tire rubbing. I still plan to flush the vent once a year to reduce the possibility of dirt and dust reaching and blocking the actual gas cap vent.
 

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Giggity!
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Personally, I think it may be like a hummingbird feeder effect.
Synapse: If the bike sits in the summer sun, pressure builds in the tank. The vent relieves this pressure to atmosphere. Maybe the vent tube also works to prevent vacuum in the top portion of the tank.
Lets say the vent tube is partially blocked. When the rider begins his ride, fuel is removed from the tank through gravity feed to the carbs. As the fuel leaves the tank, pressure is reduced. There may also be a cooling effect on the tank as it moves through the air, further reducing pressure in the tank. I would think that at some point, the pressure may be reduced to vacuum. At some point after that, there may be just enough vacuum in the tank that gravity can no longer pull the fuel through the lines. Fuel flow slows, maybe starving the carbs. After the engine dies or the tank is opened to check for fuel, air is allowed to enter either through the carbs for a “burp” or the upper portion of the tank is restored to atmosphere respectfully. Just a thought.

Good luck with the fix :).
That's all fine & dandy except for the fact that our bikes are vacume fed & not gravity fed.
 

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That's all fine & dandy except for the fact that our bikes are vacume fed & not gravity fed.
No, they are gravity fed. The only "vacuum" is the switching aspect...meaning the carb produces a vacuum that causes a diaphram in the petcock to move, allowing the fuel to flow down into the carbs...by gravity ...same as sticking a hole in the bottom of a bucket...the carbs are gravity fed.

This is why the vents off the carbs that go into the right airbox must be at atmospheric pressure. ..because the float bowls must vent for fuel to flow properly. Lower...or higher.... pressure would cause problems.


KM
 

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That's all fine & dandy except for the fact that our bikes are vacume fed & not gravity fed.
The venturi suction created by aspiration is not very strong. Also, the suction effect would not act directly on the system above the needles, would it ? Wouldn't the float vent also restrict the suctions effect ? I know I'm out of my element here. I'm always up for some learnin'. :beerchug:
 

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The venturi suction created by aspiration is not very strong. Also, the suction effect would not act directly on the system above the needles, would it ? Wouldn't the float vent also restrict the suctions effect ? I know I'm out of my element here. I'm always up for some learnin'. :beerchug:
No you got it, but the "suction created by aspiration " actually is pretty stong. It not only pulls fuel up those tiny holes but shoots it towards the cylnder fast enough to get by the valve and fill the chamber in fractions of a second.

If you ever placed your hand over a carb mouth on a running motor...you'd know what I mean. ;)

The Vulcan being a twin 750 means each cylnder displaces 350cc...or conversely... sucks in a bit over a 1/3 of a liter per intake cycle. I'm sure there is some kind of formuala to figure out what that is in inches of mercury or whatever....

KM
 

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Yes, but with out the vacum... no gas. Right? So I guess you could say it's a joint effort?
Unless you have an earlier model with a "prime" position on the petcock that bypasses the diaphram switch.

You can also install a simple on/off fuel valve and the bike will run fine.
The only reason they made the "vacuum" petcock was for liability issues of something causing the float needle to stick open letting the fuel drain out into the bike and the floor.

What you are saying is something like the reason a light bulb lights up is not just because of the electricity going to it, but because you flipped on the switch. In that way is it a "joint effort" of your finger moving the switch and the electricity going through the wires in your house. So..

Lets not forget then the effort of those producing the electricity that goes to your house, (or the oil company that offers the gasoline to you at the pump) or the hydro electric system that moves the generators or the guys drilling for the oil....if you want to say it is a joint effort...you have to include everyone.... ;)


KM
 

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No you got it, but the "suction created by aspiration " actually is pretty stong. It not only pulls fuel up those tiny holes but shoots it towards the cylnder fast enough to get by the valve and fill the chamber in fractions of a second.

If you ever placed your hand over a carb mouth on a running motor...you'd know what I mean. ;)

The Vulcan being a twin 750 means each cylnder displaces 350cc...or conversely... sucks in a bit over a 1/3 of a liter per intake cycle. I'm sure there is some kind of formuala to figure out what that is in inches of mercury or whatever....

KM
I'm totally on base with you Knife. But I think it is MUCH easier to stop the flow of fuel than the flow of air into the throat of the carb. I think the suction on the fuel is only venturi. If you close the system by placing your hand over the throat, you will definately get strong air suction from the cyclinder motion. But I am not sure exactly what amount of suction is on the fuel in an open system with no air obstruction (hand removed).
 

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Discussion Starter #18
VN750 Dies with less than a half tank of fuel

Many many thanks to everyone responsonding to my problem. It seems to me that I might have been a victum of POOGS!!!!!!!! All of the responses seem to be right on target. A special thanks goes out to Chris G. of Portland, OR. Your repair instruction was like a cookbook on how to fix something, thanks for your time on how to disassemble the fuel cap and preventing me from loosing small parts. I hate that when it happens!
So I went out and attacked my bike wanting to fix this pain in the #$&*@ problem once and for all. I just finished cleaning the fuel cap and the bad news is, I found nothing. However, I can't tell you how many times I repaired things and not knowing how or what was the cause. Maybe this will be the same thing. Win or loose, I learned something.
I'm down in the Tampa Bay area, the tempertaure is mild and my tank is at 1/2 full. The first chance I get I will be riding to see if this thing burps on me again. I will keep everyone advise if this repair was a go/ no go. Again, thanks to everyone for your input.
 

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wem416,
The only other piece of advice I can think of, would be to keep the fuel lines short, and direct to the carbs. No loops or anything. I had some external fuel filters on mine at one time. In order to get them in, I had to route the lines differently an had a horizontal section in both lines. I could see in the filters (because they were the glass casing style) that they would not stay full of fuel when I had been riding at highway speeds. I was having some slight POOGS symptoms at the time. After removing them and routing the lines back properly, the bike ran normally again. I think any air bubbles caught in the fuel line serves to restrict the flow of fuel to the carbs.
 

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...I just finished cleaning the fuel cap and the bad news is, I found nothing...
POOGS is very predictable;
  • 1/2 tank of gas or less
  • Ride for a few miles
  • Stall as if out of gas
  • Open gas cap for 3-5 minutes
  • Bike starts like there is no problem (maybe a few extra cranks)
  • Repeat
I'll assume by the 'found nothing' that you also found no evidence of debris on that piece of paper in front of the rear wheel during the flushing of the vent line (you did not say). Note that the entire air path to and from the gas tank must be clear in order to prevent POOGS.

If you still have POOGS symptoms, then go back and make sure that the entire air path to and from the gas tank is clear and that the check valves within the gas cap are functioning.

Another approach to testing is to fill the gas tank, go for a long ride, long enough to use up a good amount of gas, then stop and listen to the gas cap. If you hear a slight whistle, then the gas cap vent is working (i.e., air is being sucked into the gas tank) and your problem may lay elsewhere.

Good luck and let us know the results.
 
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