the pipe was not fitted after 2002

 

Mines a 2001 and it is fitted, just not to anywhere. Anyone know???

 

Anyone know???

Yes, I replied to you at Tigertriple.

 

The fuel pressure regulator hose (side of the fuelpump pannel) connects to a small port under the airbox next to the crank-case breather hose.

Looking down at the bike from the driver's position... 3rd cylinder has the air inlet for the ECU, Crank breather, and FPR vacuum hose connect in that corner.

Dan

 

Not nit-picking but it's a stretch to call it a 'vacuum hose' - it is not of any real consequence if not connected to the airbox. In absolute terms, the airbox pressure may be slightly below the ambient atmospheric pressure, but not significant enough to make any real difference to the effective regulator pressure.
However if there is a spigot on the airbox that was intended to receive that line, and it is unconnected then there is an open orifice to pull 'dirty' air (albeit very low volume) though it.

 

Well, you are kinda nit-picking. It does, actually transmit a variance in air-pressure... therefore, it's considered a vacuum line. Although, it could be a breather... but, hey... who's nit-picking.

 

On 955 Sprints that vent (and that is all it is just a vent) originally went into the air box using a rubber hose. On my 02 and 04 there wasn't even a hose. Like I said it is just a vent so when the regulator diaphragm moves up an down the pressure can equalize. That isn't the pressure in the fuel system I'm talking about, I'm talking about the pressure on the outside of the diaphragm. The amount of dirt in the air is totally irrelevant to the operation and long term use of the device.

 

^^^ It's interesting that in light of such an incredible 'vacuum' that Triumph determined it wasn't worth bothering with after about 2002. And also interesting that they didn't require a vacuum hose, but just used a thin-wall rubber tube attached to it
If the airbox is designed correctly, it should not be at negative pressure wrt ambient

.. .Like I said it is just a vent so when the regulator diaphragm moves up an down the pressure can equalize. ...The amount of dirt in the air is totally irrelevant to the operation and long term use of the device.

It's not really a vent either - the regulated fuel pressure is differential to whatever the absolute pressure is at that side of the diaphragm.

My reference to 'dirty air' was nothing to do with the FPR operation - it was that if the port on the airbox (that normally goes to the FPR) was left unterminated, it would be an avenue for unfiltered air (& I stressed minimal volume) into the clean side of the airbox

 

I can confirm that on my '02 Daytona 955i there is no OEM pipe connecting the fuel pressure regulator/equalizer to the airbox (or anywhere else for that matter!); it simply 'vents' to the open air.

 

Lets call it a pneumatic line then, as it carries air , whether at pressure or vacuum its certainly not hydraulic(oil).

My understanding is that the line is supposed to allow the fuel regulator to wait a bit longer before bleeding back into the tank, thus the fuel pressure can raise a bit more.

Now ...when would you want to do this, well you may want more pressure in the line under high load conditions like acceleration from a stop, when you might crank the throttle open a bit more and you need that increased squirt, like they do on carburettors that have a piston to squeeze more fuel in with the throttle movement.

It may be only a small vacuum or pressure signal, but it operates a diaphram that may not need a large signal to operate.

Basically it transmits the load conditions of the engine straight to the regulator to create a higher fuel pressure for the injectors by raising the operating pressure of the regulator temporarily.

The injectors of the 955 are much larger and flow more than the 1050 , although the ecu is slower and older and therefore the injectors may be compensating for that as does the pneumatic hose.

 

The Fuel Pressure Regulator maintains a constant differential pressure across the diaphragm.
The simple fact is that the 'reference' pressure on the Triumph is connected to the airbox (or not) and NOT to the intake(s) - so the pressure in the airbox does not really change that much.

Most autos (and some other bikes - like my Suzuki TL for example) use the TB intake as the pressure reference - that can certainly be at a different (reduced) pressure (or vacuum) - but in the Triumph, not the case.

It will make no discernible difference if you connect the hose or not - is essentially looking at atm pressure regardless.

 

On sagem ECU's the pressure regulator connects to the airbox. As the filter blocks up the regulater reduces the fuel pressure and keeps the fuel mix within the target values and emissions within spec. A simple and elegant device.
Some dozy mechanics are unaware of this important function and forget (don't bother) to connect it correctly.

 

I assume then that the designers of the Tiger are "dozy" as they deleted the connection on later bikes like mine (which of course does have the Sagem ECU).

Anything which tries to compensate for the filter getting blocked up would be very poor engineering IMO as proper servicing will ensure it never happens.

 

Even if the owner neglects to change a restricted air filter the connection to the regulater will avoid bore washing through rich fuelling and emission transgressions, all good things. I referred to dozy mechanics ignoring a fitted pipe Ian and not the factory. On your motor the barometric air pressure sensor alone took over the job of watching your air filter. The older with a pipe was belt and braces.

 

Ja but..............the factory took the trouble to seal the port in the air box which the dozy mechanic leaves open to ingest dust!
OP question has been answered.

 

found a clue as to the use of the hose on Fuel regulator



Taking it further, I found this in a fuel pressure gauge for motorbikes instruction manual.
http://www.probike.co.uk/downloads/service-tools/fpt kit instructions v2.pdf

Start engine - Let idle.
• If your vehicles fuel system uses a vacuum actuated (compensated) fuel pressure regulator then fuel pressure should drop approximately 3-10 psi, depending on manifold vacuum.
• If your vehicles fuel system uses a fuel pressure regulator without a vacuum port than fuel pressure should remain constant during both key-on-engine-off and idle.

this seems to indicate that the pneumatic hose allows the fuel pressure regulator to lower the fuel pressure on idle and likely cruise conditions for more economy.

certainly squashing the regulator with a hammer will lift the fuel pressure, so this line sucks or blows at the same item according to engine needs.

 

I see this is an old forum post which has recently been commented on, something that is often frowned at on forums, however it is probably why i found it.

I have recently acquired an 885i and investigating high revs on startup the vacuum hoses are shot to bits. However i had the same questions which have been answered. I will connect my airbox to the fuel pressure regulator. On my bike one of the vacuum hoses had a T piece inserted and a connection to knowhere. So i had an airbox hose that should have been connected to the fuel pressure regulator both left open and a T pice on the vacuum side with a hose blocked off.

I cant find any versions of diagrams with a T piece in this hose. Can anyone tell me what this was intended to do. I have a 2000 885i on a t700 frame

 

a bit late reply i know but only just seen this post as i had a question regarding the fuel pressure regulator. but i think this post has answered it.
on my 885i there should be a thin rubber hose connecting it to the airbox. after doing a full service, i couldnt remember what was connected to the regulator as the pipe comes from the other side of the engine. sorted now i think.
in regards to the t-piece on your vac line, perhaps it was connected to a scott oiler or similar?

 

Having trouble with me 885i, very little info online. Took the tank off to respray it. Put everything back together but cuts out on Idle, even when gearing down, if you hold the clutch for a few seconds, engine drops to idle and cuts out. Havnt a clue why, really stuck

 

Did you also remove the airbox? If so, check your hoses from iacv to the throttle bodies. You took fuel pump plate off tank. You may need to remove again if you can't see anything obvious with throttle body hoses,