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Love My Baby
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1,165 Posts
Discussion Starter #1
Tonight I'm riding 75 mph on the Florida turnpike, near but not quite empty on gas. Slight sputter so I turn the petcock to Reserve. Doesn't help and I pull over to the shoulder as the engine dies. I pop open the gas cap to let it breath (in case of POOGS). It won't start. 20 minutes of trying, almost killed the battery. Then I call my dad to bring me some gas because I'm thinking it must be out. Just as I hang up I try one more time to start it up, and BANG, SHE STARTS RIGHT UP!!! Ride, home, fill the tank and charge the battery. Like nothing ever happened.

WHAT THE **** HAPPENED? Anyone able to help?
 

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DelmarvaBiker
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15 Posts
Same thing happen to me last month. Riding along low but not out of fuel and sputter, sputter, dies. I tried the reserve and no such luck on a refire. Sat on the side of the road for 15 minutes and she fired right up and has run fine ever since. I'd sure like to know what caused the sputter and die issue.
 

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Registered
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796 Posts
It is possible that there was water in the bottom of the tank that finally got flushed through the carbs. One thing that I do, every time I am on the highway, I turn it to reserve to clear any water out of the tank. The higher speed and faster running fuel helps keep it from cutting out.

Other possibilities would be crud at the bottom got sucked to the reserve screen and after sitting the suction was released and was able to get fuel or the float got stuck down when the carbs were drained of fuel and then released after sitting. If the floats stuck down it would flood the engine and you would smell the fuel but after sitting it would evaporate enough to fire.

I would more likely think that it was water if you rarely turn it to reserve. Fuel additives help but there is a chance of getting a good dose of water when fueling up and you don't have any additive handy.
 

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Undercover Sportbiker
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1,097 Posts
Gas is on both sides of the tunnel. Typically, you can "run out of gas" but once it gets parked on the side stand, it miraculously fires back up. That's because, due to the lean angle, the gas gets sent over to the left side of the tank, by the petcock.

A good way to get an extra few blocks if you run out is to pull the choke. There's usually enough gas left in there to get you a little bit farther down the road.
 

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Premium Member
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812 Posts
Water and crud notwithstanding, the same happened to me when I first got the bike and I realized that I waited a little too long to switch the petcock after I felt the sputter. At 75 you probably have less time. What I suspect is that as the fuel gets a little below the feed tube you suck some air into the fuel lines and break the suction between the tank and the carbs. After a while of standing there gravity does it's job and you again have a continuous flow.
 

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Registered
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83 Posts
Had the identical problem with mine. I tried all the fuel stuff and finally changed the Ignition switch.
When I opened it up all the contacts were burnt black. I believe this caused high resistance and heat which disapates with time. Then varoom, it starts right up.
The contacts can be cleaned but for myself I went with the new switch.
Oh by the way, haven't had any problems since then.

Joe
 

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Super Moderator
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11,927 Posts
WHAT THE **** HAPPENED? Anyone able to help?

Sounds like the classic Phantom Out of Gas Syndrome. (POGS) Always seems to be just before you need to switch to reserve.

Many theroies have been posted, most concerning poor venting of the gas cap. Happened to me twice.

There is a very short window of oppertunity for when the bike begins to cough for gas and how quickly you switch over to reserve. Take a nano second too long and the bike dies, due to the float bowls emptying.
This then means you have to crank the bike several times just to fill the carbs again, and then wait for the battery to snap back.

The 2nd time I had this happen I just cranked her over 5-6 times and sat down and waited 15 minutes. Then walked back and she fired right up.


I believe the condtion is from a number of factors, venting being only one of them, fuel level the next and ambient tempature the 3rd.


As long as you have a good (AGM) battery, the bike always seems to fire up if you just wait a bit before trying again. Many suggest keeping a spare key in the gas cap so you can open it at the first hint of POGS. I never had the chance to check this fix out, but a few swear it will work.


KM
 

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Sounds like the classic Phantom Out of Gas Syndrome. (POGS) Always seems to be just before you need to switch to reserve.
......
If it is POOGS then it will not go away until the gas cap vent and vent line have been cleaned. 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. Below is my writeup on how I solved my POOGS problem.
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.


Step 2: Clean the gas cap vent mechanism

1. Open the gas cap and remove the key.
2. Cover the tank inlet tube with tape or a piece of paper to prevent dropping things 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 during removal. Inspect the latch, clean as necessary (chances are this is NOT where the problem is), then set aside.
5. 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.
6. 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.
7. Remove the two short screws at the base of the gas cap vent, but DO NOT yank the vent off yet.
8. 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.
9. With the vent assembly removed, inspect the gasket for tears or bulges. Spray with carb cleaner (just a little) and wipe with a clean cloth. Inspect the cloth for signs of debris.
10. 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, 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.
11. Now check the vent hole. 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? Unplug the holes and clean the channels.
12. Reassemble.


Step 3: Repeat Step 1 frequently (at least once a year) to prevent this from happening again.

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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IBEW 915 Electrician
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115 Posts
Had a similar problem. I had my carbs cleaned and the tank drained and cleaned three months before this happened. Went riding and pulled back by the house to retrieve an item. About three minutes later I tried to start the bike and it wouldn't start, sounded bad, too. It took a wait of about 15 minutes before it was back to normal. No problems since.
 

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Love My Baby
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1,165 Posts
Discussion Starter #10
I'm thinking that at highway speeds my fuel cut off before I switched to reserve. That put air in the line and broke vacuum. Just took a while for gravity to let fuel back in and vent out the air.

QUESTION: Does opening the throttle send gas downstream if the engine is not running? If not, does it do so when the start button is depressed but before the engine starts?
 

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796 Posts
I'm thinking that at highway speeds my fuel cut off before I switched to reserve. That put air in the line and broke vacuum. Just took a while for gravity to let fuel back in and vent out the air.

QUESTION: Does opening the throttle send gas downstream if the engine is not running? If not, does it do so when the start button is depressed but before the engine starts?
Every time you twist the throttle you give the engine a dose of gas. If you run out of fuel in the tank you can go approximately 1 mile before it will cut out. Yes there is a chance of your carbs getting air bound when this happens especially on a warm engine (almost like vapor lock)and it will act the same way. The petcock is vacuum activated except on 80s models with the prime selection so basically when this happens you just have to keep churning until the carbs are full again. Using the choke will help pull the gas faster with more vacuum but on a warm engine can flood it.

So many theories on this but I don't believe it is POOGS. Usually that happens way before you have to switch to reserve. I think it is just a case of running out of gas and waiting for the carbs to fill back up with fuel. But it IS a good idea to do the maintenance to the tank venting system at regular intervals.
 

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Linkmeister Supreme
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7,960 Posts
I'm thinking that at highway speeds my fuel cut off before I switched to reserve. That put air in the line and broke vacuum. Just took a while for gravity to let fuel back in and vent out the air.

QUESTION: Does opening the throttle send gas downstream if the engine is not running? If not, does it do so when the start button is depressed but before the engine starts?
Opening the throttle will have no effect on fuel flowing from the tank to the carb if the engine is not running.
No fuel will flow from a properly functioning petcock in the ON or RESERVE position without vacuum applied to the middle nipple.

If you have a PRIME position on your petcock (early models only `85 to maybe `89?), it should fill the carb bowls without cranking the engine over to apply vacuum. (I say should, because one member (niterider?) in a post last week said his didn`t work that way. Maybe a faulty petcock???)

I`m not sure how opening the throttle will affect vacuum to the petcock while cranking the starter over.
(I think that you will get more vacuum signal with the throttle closed, as I think about it, but I`m not positive about that.)

After running out of fuel for whatever reason, after refueling or switching the petcock from run to reserve, or vice versa, I would leave the throttle closed while cranking to fill the carb bowls, until I hear the engine try to start.
 

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Super Moderator
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11,927 Posts
Every time you twist the throttle you give the engine a dose of gas.
Just want to point out this only will happen if the motor is running...or at least turning over. The pistons need to be going up and down to "suck" in the fuel from the carbs.


I do not think the vacuum line from the carb to the petcock works any different if the throttle is open or closed...as it is , again , the pull of the pistons (that are in the "intake stroke" ) that create the "vacuum" inside the carb.

The amount of vacuum for the fuel to flow is fairly small...if the vacuum line (to the petcock) was effected by the throttle being open the bike would not run. (You'd run out of fuel every time you opened the bike up)


When you hit the starter, the motor cycles, and you create the vacuum for the fuel to flow from the petcock. This of course stops the second the motor stops turning, so that is why it may take repeated tries to fill the carb float bowls if they empty.

KM
 
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