fuel tank breathers
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Please can you post items for sale or wanted in the correct For Sale section. Items / bikes for sale here will be removed without warning. Reasons for this are in the FAQ. Thanks
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hoppy41
- Settled in member
- Posts: 41
- Joined: Mon Jun 24, 2013 12:11 am
fuel tank breathers
Hi. Can someone help. Having fuel starvation issues. Why are there 2 breathers on back of tank. One narrow one fat ? I think my narrow ones blocked. Do they both have to be clear ? Dave *confused* 
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Superjack44
- Familiar Member
- Posts: 272
- Joined: Sun Mar 08, 2009 8:52 pm
- Bike owned: 1CB400 SF 1 VFR800 1 Moto Guzz
- Location: Prudhoe Northumberland
Re: fuel tank breathers
Hi The two hoses do need to be clear the larger of the two is for draining water from the fuel cap recess, the smaller of the two is the actual petrol tank breather to check if its blocked lift the rear of the tank and blow back into the tank via the end of the small rubber pipe if you cant its blocked and will cause fuel starvation issues.
Remedy is to remove the fuel cap by removing the three allen bolts holding it in place (three are dummies) and lifting the cap off the tank you will see a small rubber insert towards the right side of the tank lift this off it will reveal the breather hole I inserted a small diameter boden cable and twisted and pushed at the same time until the end emerged from the bottom where the rubber pipe fits , if you come up against an obstruction (the problem) keep spinning the cable and pushing until it clears , it might be that if you cant clear it try from the end underneath the tank .
Hint -try and make the end of the cable a bit frayed but still small enough to enter the pipe and spin it so as to keep the cable twist tight if it tends to bite into the obstruction and difficult to turn turn it the other way.
Remedy is to remove the fuel cap by removing the three allen bolts holding it in place (three are dummies) and lifting the cap off the tank you will see a small rubber insert towards the right side of the tank lift this off it will reveal the breather hole I inserted a small diameter boden cable and twisted and pushed at the same time until the end emerged from the bottom where the rubber pipe fits , if you come up against an obstruction (the problem) keep spinning the cable and pushing until it clears , it might be that if you cant clear it try from the end underneath the tank .
Hint -try and make the end of the cable a bit frayed but still small enough to enter the pipe and spin it so as to keep the cable twist tight if it tends to bite into the obstruction and difficult to turn turn it the other way.
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hoppy41
- Settled in member
- Posts: 41
- Joined: Mon Jun 24, 2013 12:11 am
Re: fuel tank breathers
Thanks for that Jack.
Have removed the rubber insert that's under cap. I can blow compressed air through tube now.
However when the rubber insert is in place and the cap closed the cap seals the breather tube.
Why does it have that rubber insert?? When it blocks breather tube when caps shut?? Left mine out.
Bikes running OK now :-)
Thanks
Dave
Have removed the rubber insert that's under cap. I can blow compressed air through tube now.
However when the rubber insert is in place and the cap closed the cap seals the breather tube.
Why does it have that rubber insert?? When it blocks breather tube when caps shut?? Left mine out.
Bikes running OK now :-)
Thanks
Dave
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Superjack44
- Familiar Member
- Posts: 272
- Joined: Sun Mar 08, 2009 8:52 pm
- Bike owned: 1CB400 SF 1 VFR800 1 Moto Guzz
- Location: Prudhoe Northumberland
Re: fuel tank breathers
That rubber is a seal between the cap and the breather pipe to stop dirt getting into the tank.
If you cant blow into the tank with the cap closed that indicates that the breather hole through the cap is blocked , however you should remember that you can only blow into the tank a certain amount before being unable to blow any further as in fact you are pressurising the tank that pipe is there as a vent to allow the fuel to flow freely.
If you cant blow into the tank with the cap closed that indicates that the breather hole through the cap is blocked , however you should remember that you can only blow into the tank a certain amount before being unable to blow any further as in fact you are pressurising the tank that pipe is there as a vent to allow the fuel to flow freely.