Gastank will not fill without delay

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Robby Tweak

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Aug 27, 2023
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Hello,

I noticed the two past times i stopped to fuel the Vmax, the gasoline level while fuelling was lowering very very slow. It took me several minutes to get it full. I had to pause several times to let the fuel level drop and then continue. I can see the bottom of the fueltank with a light.
Any ideas?
Greetings Robby
 
Blocked breather but that said I would have thought there is sufficient space around the filler to let the air escape.
Yes there is enough space around the filler so thats why it is strange. It looks like the tank is full,
(almost floating over) then i wait, i see the level go down and i can fill it further with small steps. The gas tank is not leaking.
 
Is the bike on the centre or side stand when you fill it?
Today i fuelled it with the bike on the centre stand. I was thinking the same thing. I know it sounds strange but last time the fuel light was on, so i fuelled it and after 4 liters it seems full. Not knowing that the gasoline level was slowly dropping. The fuel was almost at the top of the fueltank filler gap.
I was surprised because i thought i had to fill it with 12 liters because the light was on. Max tank capicity is 15 liter with 3 liters spare. Today i explained it to a very experienced mechanic and he also said it is a strange thing. I will record it when i go fuelling again.
 
I have the same issue with my 2004. If I stick the nozzle back in (with the flow off) the level in the tank drops some, and I can fill it more. I do this several times until it is full. My theory is that there is trapped air at the front of the tank. When on the center stand, the problem isn't as bad, but still there.
 
I have the same issue with my 2004. If I stick the nozzle back in (with the flow off) the level in the tank drops some, and I can fill it more. I do this several times until it is full. My theory is that there is trapped air at the front of the tank. When on the center stand, the problem isn't as bad, but still there.
So glad that you post this because it is hard to believe that this is happening with the big space left over the gas opening.
A mechanic told me to remove the rubber around the gas tank opening and to check if the air tube is still open. Don NOT make this opening bigger he told me, because it will affect the bike vacuüm flow.
I have not done this yet but this evening i am checking this. Hopefully this is the solution.
 
So glad that you post this because it is hard to believe that this is happening with the big space left over the gas opening.
A mechanic told me to remove the rubber around the gas tank opening and to check if the air tube is still open. Don NOT make this opening bigger he told me, because it will affect the bike vacuüm flow.
I assume your 'mechanic's' referral to the 'air tube' is the tank vent?
With the cap off the vent is irrelevant as air can escape around the filler neck.
 
I assume your 'mechanic's' referral to the 'air tube' is the tank vent?
With the cap off the vent is irrelevant as air can escape around the filler neck.
Yes correct. I think it is the problem that air can not escape around the filler neck. How strange it may sound. So what can be the sollution?
 
Due to the tank design and the tilt of the bike when on the side stand you will have an air pocket on the right (throttle) side of the tank once the fuel reaches the filler neck. You can slowly add fuel to disperse the air which will take some time or "Burp" the tank. Grab the left grip and put your thigh against the seat and tilt the bike perpendicular to the ground. This will allow most of the trapped air to escape and you can then get the tank nearly full and be on your way. I would estimate that this allows you to get another 8-12 oz in the tank, not a lot but every little bit helps with these small tanks. Also don't tilt the bike too far or you will have much more serious issues to deal with.
 
Yea I have bumped the gas handle ever since I have had my v-max just to get every drop you can get in there. Had the same problems as stated above. Never thought too much about it because I have had to do that with cars, trucks, tractors. You name it. I hope what I got in the mail today will help me, a 20.5 liter tank from Schwabenmax. All the way from EBAY. Makes buying them there a lot easier than trying to get it from German web site looked like to me. Anyway get to go further before having to stop for gas.
 
Yea I have bumped the gas handle ever since I have had my v-max just to get every drop you can get in there. Had the same problems as stated above. Never thought too much about it because I have had to do that with cars, trucks, tractors. You name it. I hope what I got in the mail today will help me, a 20.5 liter tank from Schwabenmax. All the way from EBAY. Makes buying them there a lot easier than trying to get it from German web site looked like to me. Anyway get to go further before having to stop for gas.
Nice. I also saw it on their website. Curious if the installation is a manageable thing to do or a lot of work
 
Had no time to do it so last evening i checked some things. The air vent in the picture is open. I checked the hole with a 1 mm needle and it is open. I blew air through the air hose that is connected and air is coming through. I blew air through the air vent (picture) and fuel was coming up in the filler neck. While fuelling the filler gap is not open for air because it is filled with fuel. I have to check, after blowing the vent with air, if the problem still exist the next time i gonna fill the gastank.
 

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