Tank Vacuum problem ( I think !! )

[VTRDark]

If this is the case have you used the full 19 Liter setup ie the external petcock arrangement that sits behind the tank??

Well this is where I think half the problem is as Lee has nothing to get the fuel in accept gravity.

(:-})

[Tweety]

If this is the case have you used the full 19 Liter setup ie the external petcock arrangement that sits behind the tank??

Well this is where I think half the problem is as Lee has nothing to get the fuel in accept gravity.

(:-})

Now, excuse my ignorance, but why would that be an issue? Really?!

The guys having a 19L tank on their bike to start with, haven't got anything else helping them, AFAIK... And, neither have you... So why?

The petcock is opened by vacuum, not helping the fuel flow in any way by use of vacuum... All post 2001 VTR's in the whole of Europe get's by on gravity alone...

I personally believe that unless it's now solved by unblocking the overflow, any residual issues can perhaps be traced to his earlier kinks and bends in the pipe, from having what was believed to be the wrong version Varadero tap, and perhaps the wrong angle/length/width pipe at some point...

[leevtr]

If this is the case have you used the full 19 Liter setup ie the external petcock arrangement that sits behind the tank??

Well this is where I think half the problem is as Lee has nothing to get the fuel in accept gravity.

(:-})

Now, excuse my ignorance, but why would that be an issue? Really?!

The guys having a 19L tank on their bike to start with, haven't got anything else helping them, AFAIK... And, neither have you... So why?

The petcock is opened by vacuum, not helping the fuel flow in any way by use of vacuum... All post 2001 VTR's in the whole of Europe get's by on gravity alone...

I personally believe that unless it's now solved by unblocking the overflow, any residual issues can perhaps be traced to his earlier kinks and bends in the pipe, from having what was believed to be the wrong version Varadero tap, and perhaps the wrong angle/length/width pipe at some point...

+1...As I understand it, all the vacuum hose does is open/close the petcock, bugger all else. Gravity does the rest...
Anyway, problem appears to be solved. Had the bike running fine since the blockage was cleared.

[ant76p]

i had the same problem when i had one fitted to mine .then i finally found the problem!.
it ran fine when raised the rear of the tank up but as i lowered the tank down i noticed the fuel hose which fed the rear carb ( if sat on the bike it was the hose that goes to the right of the bike) was kincking and trapping off the flow.
i never blanked off any breathers.
i bought the tank off benny hedges and had it running on a t piece(splitter) and then machined a adapter to fit to petcock .so it would help pump it via the vacuum.

[leevtr]

i had the same problem when i had one fitted to mine .then i finally found the problem!.
it ran fine when raised the rear of the tank up but as i lowered the tank down i noticed the fuel hose which fed the rear carb ( if sat on the bike it was the hose that goes to the right of the bike) was kincking and trapping off the flow.
i never blanked off any breathers.
i bought the tank off benny hedges and had it running on a t piece(splitter) and then machined a adapter to fit to petcock .so it would help pump it via the vacuum.

Mines running fine now, no vacuum required with the vara tap. The original vac hose is bunged with a bolt, ready for carb balancing.

[VTRDark]

Now, excuse my ignorance, but why would that be an issue? Really?!

Don't know where my head was at there. Is there another thread (duplicate subject) on this somewhere. Confused as there seems to be a load more posts before my one above that where not there before I posted. I may have been thinking about the orientation of the Varedo tap. I seem to recall thinking about the fuel line pointing towards the rear of the tank so getting trapped between the tank and frame or something.

Anyway Apologies Lee I wasn't being very helpful there. Glad you got it sorted in the end. Now you have the 19L I have a feeling you will keep this Storm for longer than your other bikes. 19L is the one thing you have always wanted.

(:-})

[rollingthunderx2]

The fuel delivery does not rely on gravity, it is sucked out of the tank by the fuel pump, although it will still run with a bypassed pump.

[VTRDark]

it is sucked out of the tank by the fuel pump

No fuel pump on these. They work of the Vacuum. Gravity should work OK as long as there are no kinks or strange roller coaster type routing for the fuel lines. A fuel pump or vacuum is just a helping hand added to it. IIRC I think it also serves as a safety measure to stop the cylinders flooding with fuel if the float valve/s fail in the carbs.

(:-})

[leevtr]

it is sucked out of the tank by the fuel pump

No fuel pump on these. They work of the Vacuum. Gravity should work OK as long as there are no kinks or strange roller coaster type routing for the fuel lines. A fuel pump or vacuum is just a helping hand added to it. IIRC I think it also serves as a safety measure to stop the cylinders flooding with fuel if the float valve/s fail in the carbs.

(:-})

I spoke to a guy who's owned Storms and teaches motorcycle mechanics about this, and the vacuum hose merely opens the diaphram in the petcock, gravity does the rest.

[rollingthunderx2]

Te Varadero has a fuel pump but the Storm hasn't. so that's one less thing to go wrong, as the pumps are crap.
Anyone with a faulty fuel pump, most of them are the same Mitsubishi make, and repair kits can be bought here.

http://www.davidsilverspares.co.uk/grap ... _large.jpg

The vacuum only opens the diaphragm on the fuel tap,the suction from the carb only allows fuel to flow when the engine is running.
it is not connected directly to the fuel, so cannot "assist" the flow and does not suck the fuel into the carb.

[VTRDark]

Mmm interesting I always thought that a vacuum or pump would also help push the fuel through along as it's drawn into the float bowl hence the reason for not having lines with kinks in them or running like a roller-coaster. Earlier bikes that where gravity fed would have the tank up high or the carbs low ie tank higher than carbs so gravity can take over.

The tap and/or diaphragm is simply there as a way of shutting the fuel off. If it's gravity fed the only thing to stop the fuel flowing is the float and valve. So if either of them fail then fuel could trickle down the intake tract and through an open inlet valve filling the cylinder. When you go to start the bike it could cause a hydraulic lock https://en.wikipedia.org/wiki/Hydrolock

(:-})

[rollingthunderx2]

Yes that's right. But if the carb float needle has not seated, dirt etc, then the fuel will overflow out of the carb overflow vent.
Not usually into the cylinder.
Most Viton tipped needles are pretty reliable, but I personally turn the fuel off on bikes with a tap.
Vacuum fuel taps, are a bit like an automatic choke on a car..a convenience that isn't really necessary.
On a bike with a vacuum fuel tap,IE no manual tap, when the engine turns over and the piston sucks through the carbs, a vacuum pipe attached between the carb throat and the fuel tap sucks open a rubber diaphragm which is also a valve to control the flow of fuel out of the tank.
You can check its working by taking the tank off and sucking on the tube.If you suck and fuel comes out of the fuel line..not the vacuum pipe you are sucking...it's working. If it isn't working you can block off the vacuum at the tank end and carb and just cut a bit out of the diaphragm to let the fuel through..in an emergency.......
A carb will operate as long as the fuel level is above the float bowl.and usually at the same level approx as the outlet of the main jet tube.
Its the same as a toilet cistern, and basic Victorian technology, it has stayed the same because it was simple and worked.

Still does'nt explain why a Varadero has a fuel pump , ..at the front of the engine by the oil filter..?? WHY? lol

[Wicky]

Still does'nt explain why a Varadero has a fuel pump , ..at the front of the engine by the oil filter..?? WHY? lol

Is it because the lowest capacity of the Vardero tank is below the height of fuel entering the carb/FI so it needs to be pumped uphill to overcome gravity

Bypassing the pump allows gravity feed and it will work if the fuel level in the tank is not below the carbs.

http://users.bart.nl/~stikfort/new_inte ... ypass.html

[rollingthunderx2]

That must be the longest fuel pipe on any bike, as the pump sits by the oil filter!
Maybe there could be a market for an underslung pumped VTR aux fuel tank....