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Water getting in gas tank through vent hose?


GrahamLFCkeeper
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Hi all, hope you are all well.

I get a stuttering when riding in the rain... I've checked everything and until now it's left me stumped till I found an 11 year old (!) comment from @frankdsays ....

"Is there any chance you have water in your gas?? I've had that problem with both of my Ventures. The gas tank vent hose is right in front of the rear tire. When you're riding through a downpour water can be drawn up and into the gas tank. It shows up when you open the throttle. Then the water that accumulates in the carb bowls gets drawn into the main jets and the bike stumbles"

 

If its the case water is getting into the tank via the gas tank vent hose, anybody got a fix?

 

Cheers 

Graham 

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I've personally never heard of that happening, not saying it can't, but I've ridden through some darn near hurricane rain and never run across any symptom like that. Have you considered that it might be something electrical that when it gets wet causes the issue?

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7 minutes ago, Squidley said:

I've personally never heard of that happening, not saying it can't, but I've ridden through some darn near hurricane rain and never run across any symptom like that. Have you considered that it might be something electrical that when it gets wet causes the issue?

I almost sure it's fuel related ... the reason I've got this in my head (after seeing it)... the other week whilst in light rain, she ran fine until I went through a puddle .... after that it started stuttering and struggling with low power  

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Hey Graham,

If this is indeed the issue, then go to a lawn mower shop, (or Tractor Supply) and pick up a small inline fuel filter that will fit the diameter of the overflow line. POINT THE FLOW ARROW OF THE FILTER TOWARDS THE GROUND,  (Away for the gas tank) to allow the vapors to pass through the filter. These filters have a crude backflow preventer which will keep the water from getting sucked into the gas tank. II personally have only seen this on two First Gens. and I used this cure for both. As always Graham, good luck with this project!

Earl

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Hey Graham,

I apologize, my friend! I just checked your profile AFTER I posted about this thread. Tractor Supply might be a bit of a ride for you, LOL!! Surely you must mow grass in the UK, and have lawn mower repair shops? We have a farm supply store chain in my area called Tractor Supply, and over the years I have solved many problems with my Ventures by shopping there, and thinking "Outside The Box" so to speak. I am sure you have a store similar to this in the UK. One more thing Graham, After you have added the filter, if the filter hangs too close to the ground, cut off some of the overflow line to return the end of the filter to it's original position.

Again, I apologize for not paying closer attention to your location. But rest assured, the fix is sound advice!

Earl 

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So heres the thing about the tank vacuum vent line, down around the fuel filter or where the fuel filter is suppost to be is a tip over valve in the vent line. at the end of the metal tube coming out of the tank is a very small orifice, now take in the langth of the hose, thats a lot of stuff for enough water to travel through and contaminate several gallons of gas. the best way to see if you have contamination is to pull the hose off of the petcock, use a try clear bottle to collect a sample from the reserve position on the petcock. if you are getting water into the tank you will see water at the bottom of the sample. if you do have water you may look into the gas cap has being the problem.

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They way you describe the issue (and I do not mean to sound like a skeptic here )  but let me ask two questions. ! does this happen almost immediately upon riding in the rain or hitting a big puddle and  does the issue clear up by itself after things dry up. I ask this because  if the answer is yes to both questions I tend to doubt its water entering the fuel tank. Whether the cause is a faulty cap or water drawn in through the vent line the issue would not pop up immediately, nor would it go away just because it dried up outside because it takes time for enough water to enter the tank then trickle down through the gas to the bottom and then fill the bottom of the tank to the point were it can be picked up by the pickup tube. Then once it accumulates to the point were does become a problem it would not just go away when things dry up, once enough water is in the tank to cause a problem it is there to stay and should it accumulate in the fuel bowls to were the bike quits or will not start the would not start again until you have drained the fuel bowls and tank of the accumulated  water. There fore Like steamer I would look towards and electrical issue. Also Steamers suggestion ( which is a good one ) of draining fuel out of the fuel hose at the tank valve to check for water  also needs to gain a certain level before it will come out. Try draining from the carbs as well to see if water is in the float bowl. Both are best down after the bike has sat for a bit to allow the water and gas to separate. You can also try acquiring some water detection paste. smear a bit on a stiff but flexible makeshift dip stick and reach into the bottom of the fuel tank through the filler. The paste usually green will turn a purplish pink if it contacts any water.

Next time the bike quits in the rain spray and wash down your coils, plugs and plug wires with a penetrating oil such as WD40 or equivalent and see if the bike restarts. You can also try wetting the bike electrical system down with a spray bottle of water a spot at a time to see if it causes an issue Or hose the whole bike down really well in the dark and then watch for arching or as we mechanics say look for Christmas lights. Water will often create carbon tracts on the external surfaces of high voltage parts of the ignition system. If you nothing shows up remove all your plug wires and apply a generous amount of dielectric grease inside the boots and sockets and reassemble. you could take it one step further and replace the plugs and wires while doing this

Another source of rain induced cutting out I have found on many bike mostly Harley's, Is the ignition switch. Over time they develop a green powder in the switch and/or connectors. every time this powder ( we call Fretting ) gets wet it shorts out the electrical system enough to create an issue but not enough to blow a fuse. Try flushing the switch and connectors with electrical cleaner and a small brush were you can, With a sealed ignition switch stick the straw into the key hole and flush well alternating between spraying and turning the switch back and forth with the key. Follow up with a spray such as ACF50 or equivalent and saturate the ignition switch well. While your at it go over all your connections clean and apply dielectric grease to your connections.

Edited by saddlebum
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I've had this identical problem with both of my 1st. Gen. bikes.    The first time I had it, is was on a trip and had ridden most of the previous day in rain.   After a bit the bike ran real rough, but if I gave it full throttle, it would run better for a little bit.    I put up with the poor running all the way home, and by after about 300 miles it was better.    Then I was going into work at 3AM and it got real bad.    I fought with it and by that afternoon I was pretty convinced that it was water in the tank.   I pulled out the fuel filter and blew it out putting the contents on my driveway and you could see the water separated from the gas.     I pulled the petcock from the tank and drained the water out of the bottom of the tank.    Then I opened the carb. drain screws and drained the carbs.   Once again I could see water in the gasoline drained from the carbs.      Put it back together and it ran great.    A couple of years later, I got caught in a gully washer, and the bike began to run rough again.     When I got home, I had to drain the water again.     This was before there was 10% Ethanol in gasoline, so water would just lay in the bottom of the tank until it was drained.      I figured the only way for rain water to get into the tank would be through the vent.    I traced it's path and saw it was right in front of the rear tire and as gas was drawn out of the gas tank, a vacuum would form and it would draw some of the water that was was in front of the tire, which would go up into the gas tank.     I cut a slit in the vent hose so that a strong vacuum wouldn't form at the lower end of the vent hose.     I never had problems again, until I purchased the 89.     I hadn't had this problem for so long that I never did anything to prevent this on the new(er) bike.    My wife and I were on the way to Maintenance day and on the Ohio Turnpike it rained hard for a bit, and the bike started missing.    I knew what was wrong but couldn't do anything where we were, so we just soldiered on.    Now the gasoline was mixed with ethanol, and could absorb some water.    After we filled it up with fresh gas, it got better.   After the 2nd fill, it was mostly cured.      By that night it was fine.      After we got home, I cut  a slit in this vent hose also.

To verify if you have water in your tank, pull the fuel filter, hold it vertically with the filter element up, and then blow through it (using a hose) on to a hard surface.     Look at what's on the ground and if you have water in your tank, you should see some mixed in with the gas.

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I have had a bunch of trouble running the low grade fuel with miss fire and running ruff ...I have found that sparks plugs & air filter  play a big role in a good running engine ...Sometimes heat will cause condensation  in the fuel .The high alcohol content in the low grade fuel had been found a big problem by many riders out here ...For the last 10 years I have been using a fuel conditioner in all my fill ups ( I buy in bulk )...I know they keep on telling us that the low grade will work  just fine ...There many words I have heard to describe the use of ( some of them I cannot use on line )  low grade fuel in bikes built before 1985 , many of them have a compression ratio of 10.5  ... . I belong to the Antique Motorcycle Club of Manitoba and I have found that there is a great amount of good information the guys come up within the club ...www.amcm.ca

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I have posted this before but will again since it may be useful to some. It lists ethanol free gasoline locations.

https://www.pure-gas.org/about

https://www.pure-gas.org/chart

Interesting FAQ from the above website;

Can I test gas myself to see if it contains ethanol?
Yes, and it's quite easy to do. Inexpensive fuel-testing kits are widely available, or you can just do it yourself:  

  1. Pour a small amount of water into a narrow jar (an olive jar works great) and mark the water level with a Sharpie.
  2. Add the fuel to around a 10:1 fuel:water ratio.
  3. Shake well, let settle for a few minutes.
  4. See if the water level has risen above the mark. If it has risen, it has combined with ethanol from the fuel.
Edited by saddlebum
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