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Discussion Starter #1 (Edited)
HELP! Missing Hoses Under Fuel Tank???

I pulled the tank last night to swap the plastic fittings for metal ones. When I was disconnecting the overflow hoses, I noticed one was connected to the small vacuum diaphram in the center of the flange, and the other hose coming off the throttle body synch hoses (vacuum line) was not connected to anything, It was wedged between the side of the flange and the rear-most overflow spout on. The shop manual shows a Y-connector coming off the 2 overflow spouts going to a down-tube, but it does not show anything connected to the small diaphram. The manual I have may not be up to date for a 2006 model. I suspect it should be connected to the vacuum line coming from the synch hoses, but the ID of the hose is too large for the nipple on the diaphram.

Could someone please post a close-up picture of this area with all hoses connected in their proper places? I think the dealer may have left the Y-connector off when the bike was last serviced, and got the lines all fouled up. I'm not too concerned about the overflow lines, since they're pretty obvious, but that small vacuum diaphram has me puzzled. Thanks.
 

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Discussion Starter #2
Nevermind. I went by the dealer and found diagrams in the parts book that match my bike's drain hoses. The shop manual has a completely different drain hose setup.
 

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Under tank drain and vacuum hose confusion 05 F4 1000

I pulled the tank last night to swap the plastic fittings for metal ones. When I was disconnecting the overflow hoses, I noticed one was connected to the small vacuum diaphram in the center of the flange, and the other hose coming off the throttle body synch hoses (vacuum line) was not connected to anything, It was wedged between the side of the flange and the rear-most overflow spout on. The shop manual shows a Y-connector coming off the 2 overflow spouts going to a down-tube, but it does not show anything connected to the small diaphram. The manual I have may not be up to date for a 2006 model. I suspect it should be connected to the vacuum line coming from the synch hoses, but the ID of the hose is too large for the nipple on the diaphram.

Could someone please post a close-up picture of this area with all hoses connected in their proper places? I think the dealer may have left the Y-connector off when the bike was last serviced, and got the lines all fouled up. I'm not too concerned about the overflow lines, since they're pretty obvious, but that small vacuum diaphram has me puzzled. Thanks.

I am having a similar problem with my 2005 F4 1000.

I see one vacuum hose and one drain hose, with same ID.

On the tank bottom plate there are two 2 drain nipples (apparently, I think that is what they are) and an additional smaller ID hose nipple on the the diaphragm valve (pressure relief???)

I remember disconnecting the diaphragm. But it doesn't make sense that it would go to drain, so it must be vacuum hose. That leaves the drain hose, but which is the proper drain port? The one closer to the front or the rear? That leaves one drain port with no hose, which is fine, but that adds to my confusion.

The F4 1000 shop manual is indeed different, showing a y connection, but I can not see exactly where it connects. I can't see the diaphragm at all.

The older 750 parts catalog I have gives no indication.

My dealer is a two hour round trip.

ANY HELP and/or DIAGRAMS are appreciated.
 

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Discussion Starter #4
Well it's been about a year, and my memory is poor, but as near as I recall, the 2 rubber lines are both connected to the cast metal overflow lines. The small nipple on the diaphragm does not have anything attached to it.
 

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Well it's been about a year, and my memory is poor, but as near as I recall, the 2 rubber lines are both connected to the cast metal overflow lines. The small nipple on the diaphragm does not have anything attached to it.
Thanks. It seems that may be the case. But I still wonder about:
1) the diaphragm valve,(fuel pressure regulator I think). Both of us seem to remember disconnecting that.... Does it use vacuum or atmospheric pressure on that side? Note that in an overpressure situation, it is important that the fuel pressure regulator operate properly.
2) If the vacuum hose goes to the drain/overflow, that could cause a problem, sucking raw fuel (or water, the service manual states one drain is fuel overflow the other is water (where would water get in?? Around the fuel filler cap??)) Either way raw fuel or water going directly into the air intake system would be a problem!!!

Maybe I answered my own question/Process of elimination....

THEREFORE: Only the Diaphragm can connect to vacuum and the other two drains, would go to the drain line :banghead:

Any other help out there??
 

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Falccopilot,
I just read another thread that states one hose is a drain for fuel overflow and the other is vacuum for the "Evaporative canister".

That would make sense. I am still unsure, but You might want to double-check you connections If your fuel overflow is sucked into the air intake, that would be a problem.
 

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The fuel pressure regulator (the vacuum diaphragm) does not have a hose connected to it at all, connecting a hose to it and to a vacuum source will cause the bikes fuelling to be weak, more than a few people have asked this question over the years!!
 

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Well now I am unsure if the diaphragm is the pressure regulator or evaporative cannister.

In either case, I do remember unhooking a hose. First time tank removed since new.

NEW PROBLEM, Fuel tank drain bolt
To add insult to injury, what I thought was the fuel tank drainage bolt now leaks.
a) When the tank was upside down, fuel siphoned out from the little port in the center (???)
b) Tank, upright, fuel pours out!!!
c) I open the fuel filler, releasing pressure and the flow stops
d) Run the bike and it flows out again.

WHAT HAVE I DONE??? I better start a new thread
 

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Seem to have gotten it together.. The left vent to vacuum and the right to the drain. Left the diaphragm open to atmosphere.

Have no idea why the drain bolt started leaking. I hadn 't touched it. Loosened the lock nut and turned the center hex head OUT and that seemed to fix it.
 
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